Action potential


An action potential is a "spike" of electrical discharge that travels along the membrane of a cell. Action potentials are an essential feature of animal life, rapidly carrying information within and between tissues. They also occur in some plants. Action potentials can be created by many types of cells, but are used most extensively by the nervous system for communication between neurons and for transmitting information from neurons to other body tissues such as muscles and glands. Action potentials are not the same in all cell types and can even vary in their properties at different locations in the same cell. For example, cardiac action potentials are significantly different from the action potentials in most neurons. This article is primarily concerned with the "typical" action potential of axons.


Active listening


When interacting, people often are not listening attentively to one another. They may be distracted, thinking about other things, or thinking about what they are going to say next, (the latter case is particularly true in conflict situations or disagreements). Active listening is a structured way of listening and responding to others. It focuses attention on the speaker. Suspending one’s own frame of reference and suspending judgment, are important in order to fully attend to the speaker.


Adaptation (Neural adaptation)


Neural adaptation or sensory adaptation is a change over time in the responsiveness of the sensory system to a constant stimulus. It is usually experienced as a change in the stimulus. For example, if one rests one's hand on a table, one immediately feels the table's surface on one's skin. Within a few seconds, however, one ceases to feel the table's surface. The sensory neurons stimulated by the table's surface respond immediately, but then respond less and less until they may not respond at all; this is neural adaptation. More generally, neural adaptation refers to a temporary change of the neural response to a stimulus as the result of preceding stimulation. It is usually distinguished from memory, which is thought to involve a more permanent change in neural responsiveness. Some people use adaptation as an umbrella term that encompasses the neural correlates of priming and habituation. In most cases, adaptation results in a response decrease, but response facilitation does also occur. Adaptation is considered to be the cause of perceptual phenomena like afterimages and the motion aftereffect. In the absence of fixational eye movements, visual perception may fade out or disappear due to neural adaptation [1]. (See Adaptation (eye).) While large mechanosensory neurons such as type I/group Aβ will display adaptation, smaller type IV/group C nociceptive neurons do not. As a result, pain does not usually subside rapidly but persists for long periods of time, but one quickly stops receiving touch or other sensory information if surroundings remain constant.


Adaptation is a decrease in sensitivity to continued stimuli. In fact, the perception of a sensation may actually disappear even though the stimulus is still being applied. For example, when you first get into a tub of hot water, you probably feel a burring sensation, but soon the sensation decreases to one of comfortable warmth even though the stimulus(hot water) is still present. In time, the sensation of warmth disappears completely. Other examples of adaptation include placing a ring on your finger, putting on your shoes or hat, sitting on a chair, and pushing your glasses up on the top of your head. Adaptation results from a change in a receptor, a change in a structure associated with a receptor, or inhibitory feedback from the brain. Receptors vary in their ability to adapt. Rapidly Adapting (Phasic) receptors such as those associated with pressure, touch, and smell, adapt very quickly. Such receptors play a major role in signaling changes in a particular sensation. Slowly adapting (tonic) receptors, such as those associated with pain, body position, and detecting chemicals in blood, adapt slowly. These receptors are important in signaling information regarding steady states of the body.


Adrenal Glands


In mammals, the adrenal glands (also known as suprarenal glands) are the triangle-shaped endocrine glands that sit on top of the kidneys; their name indicates that position (ad-, "near" or "at" + -renes, "kidneys"). They are chiefly responsible for regulating the stress response through the synthesis of corticosteroids and catecholamines, including cortisol and adrenaline. Anatomically, the adrenal glands are located in the thoracic abdomen situated atop the kidneys, specifically on their anterosuperior aspect. In humans, the adrenal glands are found at the level of the 12th thoracic vertebra and receive their blood supply from the adrenal arteries.


Areolar connective tissue


It can be found in the skin as well as in places that connect epithelium to other tissues. The areolar tissue is found beneath the dermis layer and is also underneath the epithelial tissue of all the body systems that have external openings. It is also a component of mucus membranes found in the digestive, respiratory, reproductive, and urinary systems. It also surrounds the blood vessels and nerves. [edit] Composition It is a pliable, mesh-like tissue with a fluid matrix and functions to cushion and protect body organs. Cells called fibroblasts are widely dispersed in this tissue; they are irregular branching cells that secrete strong fibrous proteins and proteoglycans as an extracellular matrix. The cells of this type of tissue are generally separated by quite some distance by a gel-like gelatinous substance primarily made up of collagenous and elastic fibers [edit] Function It acts as a packaging tissue holding the internal organs together and in correct placement.

It holds organs in place and attaches epithelial tissue to other underlying tissues. [edit] Classification Loose connective tissue is named based on the "weave" and type of its constituent fibers. There are three main types: Collagenous fibers: collagenous fibers are made of collagen and consist of bundles of fibrils that are coils of collagen molecules. Elastic fibers: elastic fibers are made of elastin and are "stretchable." Reticular fibers: reticular fibers consist of one or more types of very thin collagen fibers. They join connective tissues to other tissues.




Conveying impulses toward the central nervous system


Albert Ellis (1913-2007) (Rational-Emotive Therapy)

Albert Ellis (September 27, 1913 – July 24, 2007) was an American psychologist who in 1955 developed Rational Emotive Behavior Therapy. He was considered by many to be the grandfather of cognitive-behavioral therapies and, based on a 1982 professional survey of U.S. and Canadian psychologists, one of the most influential psychotherapists in history (Carl Rogers placed first in the survey; Sigmund Freud placed third).[1] Ellis founded and was the president and president emeritus of the New York City-based Albert Ellis Institute.[2]


Andrew Taylor Still (1828-1917)


Andrew Taylor Still (1828-1917), D.O. wrote in 1899 the “Philosophy of Osteopathy” [1] [2]  [3]


Andrew Taylor Still (August 6, 1828-December 12, 1917) is considered the father of osteopathic medicine.[citation needed] Still was born in Lee County, Virginia in 1828, the son of a Methodist minister and physician. At an early age, Still decided to follow in his father's footsteps as a physician. After studying medicine and serving an apprenticeship under his father, Still became a licensed M.D. in the state of Missouri. Later, in the early 1860's, he completed additional coursework at the College of Physicians and Surgeons in Kansas City, Missouri. He went on to serve as a surgeon in the Union Army during the American Civil War. After the Civil War and following the death of three of his children from spinal meningitis in 1864, Still concluded that the orthodox medical practices of his day were frequently ineffective and sometimes harmful. He devoted the next ten years of his life to studying the human body and finding better ways to treat disease. His research and clinical observations led him to believe that the musculoskeletal system played a vital role in health and disease and that the body contained all of the elements needed to maintain health if properly stimulated. Still believed that by correcting problems in the body's structure, through the use of manual techniques now known as osteopathic manipulative medicine (OMM), the body's ability to function and to heal itself could be greatly improved. He also promoted the idea of preventive medicine and endorsed the philosophy that physicians should focus on treating the whole patient, rather than just the disease. He became so skilled at reducing fractures, he became known as the "lightning bone setter". At the time, these beliefs formed the basis of a new medical approach, osteopathic medicine. Based on this philosophy, Still founded the first school of osteopathy -- the American School of Osteopathy (now Kirksville College of Osteopathic Medicine) in Kirksville, Missouri in 1892.




Aponeuroses (απο, "away" or "of", and νευρον, "sinew") are membranes separating muscles from each other. They have a shiny, whitish-silvery color, and are histologically similar to tendons, but are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery, and peel off by sections. The primary regions with thick aponeurosis is in the ventral abdominal region, the dorsal lumbar region, and in the palmar region.




An axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.


Brachial Plexus


The brachial plexus is an arrangement of nerve fibres, running from the spine, specifically from above the fifth cervical vertebra to underneath the first thoracic vertebra (C5-T1). It proceeds through the neck, the axilla (armpit region) and into the arm. The brachial plexus is responsible for cutaneous and muscular innervation of the entire upper limb, with two exceptions: the trapezius muscle innervated by the spinal accessory nerve and an area of skin near the axilla innervated by the intercostobrachialis nerve. Therefore, lesions of the plexus can lead to severe functional impairment.


Carl Rogers

Carl Ransom Rogers (January 8, 1902 – February 4, 1987) was an influential American psychologist and among the founders of the humanistic approach to psychology. Rogers is considered to be one of the founding fathers of psychotherapy research and was honored for his pioneering research with the Award for Distinguished Scientific Contributions by the American Psychological Association in 1956. The Person-centered approach, his own unique approach to understanding personality and human relationships, found wide application in various domains such as psychotherapy and counseling (Client-centered therapy), education (Student-centered learning), organizations, and other group settings. For his professional work he was bestowed the Award for Distinguished Professional Contributions to Psychology by the APA in 1972. Towards the end of his life he was nominated for the Nobel Peace Prize for his work with national intergroup conflict in South Africa and Northern Ireland. In an empirical study by Haggbloom et al. (2002) using six criteria such as citations and recognition, Rogers was found to be the 6th most eminent psychologist of the 20th Century and among clinicians, 2nd only to Sigmund Freud.[1]

Cardiac muscle

'Cardiac muscle' is a type of involuntary striated muscle found within the heart. Its function is to "pump" blood through the circulatory system by contracting.  Metabolism Cardiac muscle is adapted to be highly resistant to fatigue: it has a large number of mitochondria enabling continuous aerobic respiration; numerous myoglobins (oxygen storing pigment); and a good blood supply, which provides metabolic substrate and oxygen. The heart is so tuned to aerobic metabolism that it is unable to pump sufficiently in ischaemic conditions. At basal metabolic rates, about 1% of energy is derived from anaerobic metabolism. This can increase to 10% under moderately hypoxic conditions, but under more severe hypoxic conditions, not enough energy can be liberated by lactate production to sustain ventricular contractions. [1] Under basal aerobic conditions, 60% of energy comes from fat (free fatty acids and triacylglycerides), 35% from carbohydrates, and 5% from amino acids and ketone bodies. However, these proportions vary widely according to nutritional state. E.g., in starvation, lactate can be recycled by the heart. There is a cost to lactate recycling, since one NAD+ is reduced to get pyruvate from lacate, but the pyruvate can then be burnt aerobically in the TCA cycle, liberating much more energy. In diabetes, more fat and less carbohydrate is used, due to the reduced induction of GLUT4 glucose transporters to the cell surfaces. However, contraction itself plays a part in bringing GLUT4 transporters to the surface. [2] This is true of skeletal muscle, but relevant in particular to cardiac muscle, since it is always contracting. [edit] Contractions [edit] Initiation Unlike skeletal muscle, which contracts in response to nerve stimulation, and like single unit smooth muscle, cardiac muscle is myogenic, meaning that it is self-excitable stimulating contraction without a requisite electrical impulse coming from the central nervous system. A single cardiac muscle cell, if left without input, will contract rhythmically at a steady rate; if two cardiac muscle cells are in contact, whichever one contracts first will stimulate the other to contract, and so on. This inherent contractile activity is heavily regulated by the autonomic nervous system. If synchronization of cardiac muscle contraction is disrupted for some reason (for example, in a heart attack), uncoordinated contraction known as fibrillation can result. This transmission of impulses makes cardiac muscle tissue similar to nerve tissue, although cardiac muscle cells are notably connected to each other by intercalated discs. Intercalated discs conduct electrochemical potentials directly between the cytoplasms of adjacent cells via gap junctions. In contrast to the chemical synapses used by neurons, electrical synapses, in the case of cardiac muscle, are created by ions flowing from cell to cell, known as an action potential.

[edit] Intercalated disc An intercalated disc is an undulating double membrane separating adjacent cells in cardiac muscle fibers. Intercalated discs support synchronized contraction of cardiac tissue. They can easily be visualized by a longitudinal section of the tissue. Three types of membrane junctions exist within an intercalated disc—fascia adherens, macula adherens, and gap junctions. Fascia adherens are anchoring sites for actin, and connects to the closest sarcomere. Macula adherens stop separation during contraction by binding intermediate filaments joining the cells together also called a desmosome. Gap junctions allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle. When observing cardiac tissue through a microscope, intercalated discs are an identifying feature of cardiac muscle[edit] Rate Specialized pacemaker cells in the sinoatrial node normally determine the overall rate of contractions, with an average resting pulse of 72 beats per minute. The central nervous system does not directly create the impulses to contract the heart, but only sends signals to speed up or slow down the heart rate through the autonomic nervous system using two opposing kinds of modulation: (1) sympathetic nervous system (fight or flight response) (2) parasympathetic nervous system (rest and repose) Since cardiac muscle is myogenic, the pacemaker serves only to modulate and coordinate contractions. The cardiac muscle cells would still fire in the absence of a functioning SA node pacemaker, albeit in a chaotic and ineffective manner. This condition is known as fibrillation. Note that the heart can still beat properly even if its connections to the central nervous system are completely severed. [edit] Role of calcium In contrast to skeletal muscle, cardiac muscle cannot contract in the absence of extracellular calcium ions as well as extracellular potassium ions. In this sense, it is intermediate between smooth muscle, which has a poorly developed sarcoplasmic reticulum and derives its calcium across the sarcolemma; and skeletal muscle which is activated by calcium stored in the sarcoplasmic reticulum (SR). The reason for the calcium dependence is due to the mechanism of calcium-induced calcium release (CICR) from the SR that must occur under normal excitation-contraction (EC) coupling to cause contraction. [edit] Appearance [edit] Striation Cardiac muscle exhibits cross striations formed by alternation segments of thick and thin protein filaments which are anchored by segments called Z-lines. The primary structural proteins of cardiac muscle are actin and myosin. The actin filaments are thin causing the lighter appearance of the I bands in muscle, while myosin is thicker and darker lending a darker appearance to the alternating A bands in cardiac muscle as observed by a light enhanced microscope. [edit] Nuclei Cardiac muscle can be distinguished from skeletal muscle because cardiac muscle nuclei are centrally located among the myofibrils, unlike the peripheral nuclei of skeletal muscle.[3] A unique aspect of cardiac muscle is the number of nuclei found inside the cell. Skeletal muscle cells are multinucleated from the fusion of muscle cells, whereas smooth muscle cells are strictly mononucleated, and cardiac muscle cells are predominantly mononucleated in humans. In some non-human species the foetal and post-parturition cardiac myocytes undergo a change from a mononuclear cell to a binuclear cell. In some cases the myocytes further develop into multinucleated cells. Amongst most species the cardiac myocyte consists of 90% binucleated cells and 5% mono-gram and multinucleated-gram cells. The exact proportions depend upon the species in question. [edit] T-Tubules

Another histological difference between cardiac muscle and skeletal muscle is that the T-tubules in cardiac muscle are shorter, broader and run along the Z-Discs. There are fewer T-tubules in comparison with Skeletal muscle. Additionally, cardiac muscle forms dyads instead of the triads formed between the T-tubules and the sarcoplasmic reticulum in skeletal muscle. [edit] Intercalated Discs Under light microscopy, intercalated discs appear as thin, typically dark-staining lines dividing adjacent cardiac muscle cells. The intercalated discs run perpendicular to the direction of muscle fibers. Under electron microscopy, an intercalated disc's path appears more complex. At low magnification, this may appear as a convoluted electron dense structure overlying the location of the obscured Z-line. At high magnification, the intercalated disc's path appears even more convoluted, with both longitudinal and transverse areas appearing in longitudinal section.[4] Gap junctions (or nexus junctions) fascia adherens (resembling the zonula adherens), and desmosomes are visible. In transverse section, the intercalated disk's appearance is labyrinthine and may include isolated interdigitations.

Celiac plexus


The celiac plexus is located near where the celiac trunk, superior mesenteric artery, and renal arteries branch from the abdominal aorta. It is behind the stomach and the omental bursa and in front of the crura of the diaphragm, on the level of the first lumbar vertebra, L1. The plexus is formed (in part) by the greater and lesser splanchnic nerves of both sides, and also parts of the right vagus nerve. The celiac plexus proper consists of the celiac ganglia with a network of interconnecting fibers. The aorticorenal ganglia are often considered to be part of the celiac ganglia, and thus, part of the plexus. The celiac plexus is often popularly referred to as the solar plexus, generally in the context of a blow to the stomach. In many of these cases, it is not the celiac plexus itself being referred to, but rather the region where it is located. A blow to the stomach can upset this region. This can cause the diaphragm to spasm, resulting in difficulty in breathing — a sensation commonly known as "getting the wind knocked out of you". A blow to this region can also affect the celiac plexus itself, possibly interfering with the functioning of the viscera, as well as causing great pain. A celiac plexus block by means of fluoroscopically guided injection is sometimes used to treat intractable pain from cancers such as pancreatic cancer. According to Hindu beliefs, the solar plexus chakra is "the center of etheric-psychic intuition: a vague or non-specific, sensual sense of knowing; a vague sense of size, shape, and intent of being."[1] As such, some psychics recommend "listening" to it since it may help out in making better decisions in one's life on many different levels.[2]


Cervical Plexus

The cervical plexus is a plexus of the ventral rami of the first four cervical spinal nerves which are located from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medial side and vertebral (m.scalenus, m.levator scapulae, m.splenius cervicis) from lateral side. Here there is anastomosis with accessory nerve, hypoglossal nerve and sympathetic trunk.

It is located in the neck, deep to sternocleidomastoid. Nerves formed from the cervical plexus innervate the back of the head, as well as some neck muscles. The branches of the cervical plexus emerge from the posterior triangle at the nerve point, a point which lies midway on the posterior border of the Sternocleidomastoid.




Detect taste in the mouth, smell in the nose, and chemicals in body fluids, such as oxygen, carbon dioxide, water, and glucose.


Cohort study


A cohort study is a form of longitudinal study used in medicine and social science. It is one type of study design. In medicine, it is usually undertaken to obtain evidence to try to refute the existence of a suspected association between cause and disease; failure to refute a hypothesis strengthens confidence in it. Crucially, the cohort is identified before the appearance of the disease under investigation. The study groups, so defined, are observed over a period of time to determine the frequency of new incidence of the studied disease among them. The cohort cannot therefore be defined as a group of people who already have the disease. Distinguishing causality from mere correlation cannot usually be done with results of a cohort study alone.


Connective tissue


Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue.) It is largely a category of exclusion rather than one with a precise definition, but all or most tissues in this category are similarly: Involved in structure and support. Derived from mesoderm, usually. Characterized largely by the traits of non-living tissue.

Blood, cartilage, and bone are usually considered connective tissue, but because they differ so substantially from the other tissues in this class, the phrase "connective tissue proper" is commonly used to exclude those three. There is also variation in the classification of embryonic connective tissues; on this page they will be treated as a third and separate category. When heated to 190 degrees farenheit, connective tissue emits a "Vinegar Like Stench Areolar (or loose) connective tissue holds organs and epithelia in place, and has a variety of proteinaceous fibres, including collagen and elastin. It is also important in inflammation. Adipose tissue contains adipocytes, used for cushioning, thermal insulation, lubrication (primarily in the pericardium) and energy storage. [fat] Dense connective tissue (or, less commonly, fibrous connective tissue) forms ligaments and tendons. Its densely packed collagen fibres have great tensile strength. Reticular connective tissue is a network of reticular fibres (fine collagen, type III) that form a soft skeleton to support the lymphoid organs (lymph nodes, bone marrow, and spleen.) Blood functions in transport. Its extracellular matrix is blood plasma, which transports dissolved nutrients, hormones, and carbon dioxide in the form of bicarbonate. The main cellular component is red blood cells. Bone makes up virtually the entire skeleton in adult vertebrates. Cartilage makes up virtually the entire skeleton in chondrichthyes. In most other vertebrates, it is found primarily in joints, where it provides cushioning. The extracellular matrix of cartilage is composed primarily of collagen.


Coronary Ligament (Liver)


The posterior surface (facies posterior) (Fig. 1087) is rounded and broad behind the right lobe, but narrow on the left. Over a large part of its extent it is not covered by peritoneum; this uncovered portion is about 7.5 cm. broad at its widest part, and is in direct contact with the diaphragm. It is marked off from the upper surface by the line of reflection of the upper layer of the coronary ligament, and from the under surface by the line of reflection of the lower layer of the coronary ligament.


Craniosacral therapy


Cranial Technique [4] [5] [6] [7] [8] [9] [10] [11] [12] Selected Cranial Sacral Research [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34]

Craniosacral therapy (also called CST, cranial osteopathy, also spelled CranioSacral therapy) is a method of alternative medicine used by massage therapists, naturopaths, chiropractors and osteopaths, who manually apply a subtle movement of the spinal and cranial bones to bring the central nervous system into harmony. This therapy involves assessing and addressing the movement of the cerebrospinal fluid (CSF), which can be restricted by trauma to the body, such as through falls, accidents, and general nervous tension. By gently working with the spine, the skull and its cranial sutures, diaphragms, and fascia, the restrictions of nerve passages are eased, the movement of CSF through the spinal cord can be optimized, and misaligned bones can be restored to their proper position. This therapy is said to be particularly useful for mental stress, neck and back pain, migraines, TMJ Syndrome, and for chronic nervous conditions such as fibromyalgia.[1][2][3]



Skeptics existing both inside and outside the osteopathic profession level the following criticisms at Craniosacral therapy:

Lack of evidence for the existence of "cranial bone movement"

The scientific evidence for cranial bone movement is insufficient to support the theories claimed by craniosacral practitioners. Scientific research supports the theory that the cranial bones fuse during adolescence, making movement impossible. However, this research only points to fusion of the base of the skull which is not contested in craniosacral therapy and does not address movement in the superior plates. As such, this research plays no part in disproving the type of cranial bone movement as postulated by craniosacral therapy.[37]

Lack of evidence for the existence of the "cranial rhythm"

While evidence exists for cerebrospinal fluid pulsation, one study states it is caused by the functioning of the cardiovascular system and not by the workings of the craniosacral system.[38]

Lack of evidence linking "cranial rhythm" to disease

No research to date has supported the link between the "cranial rhythm" and general health.

Lack of evidence "cranial rhythm" is detectable by practitioners

Operator interreliability has been very poor in the studies that have been done. Five studies showed an operator interreliability of zero.[39]

The one study showing some operator interreliability has been criticized as deeply flawed in a report to the British Columbia Office of Health Technology Assessment.[40]


Dense connective tissue

Dense connective tissue, also called dense fibrous tissue, has collagen fibers as its main matrix element. It is mainly composed of collagent type I. Crowded between the collagen fibers are rows of fibroblasts, fiber-forming cells, that manufacture the fibers. Dense connective tissue forms strong, rope-like structures such as tendons and ligaments. Tendons attach skeletal muscles to bones; ligaments connect bones to bones at joints. Ligaments are more stretchy and contain more elastic fibers than tendons. Dense connective tissue also make up the lower layers of the skin (dermis), where it is arranged in sheets. [edit] Types It is often divided into "regular" and "irregular": Dense regular connective tissue provides strong connection between different tissues. The collagen fibers in dense regular connective tissue are bundled in a parallel fashion. Tendons, which connect muscle to bone, derive their strength from the regular, longitudinal arrangement of bundles of collagen fibers. Ligaments bind bone to bone and are similar in structure to tendons. Dense irregular connective tissue has fibers that are not arranged in parallel bundles as in dense regular connective tissue. This tissue comprises a large portion of the dermal layer of skin.


In the anatomy of mammals, the diaphragm is a shelf of muscle extending across the bottom of the ribcage. The diaphragm separates the thoracic cavity (with lung and heart) from the abdominal cavity (with digestive system and urogenital system). In its relaxed state, the diaphragm is shaped like a dome. It is controlled by the phrenic nerve. In order to avoid confusion with other types of diaphragm, it is sometimes referred to as the thoracic diaphragm. Any reference to the diaphragm is understood to refer to this structure. It is crucial in respiration: in order to draw air into the lungs, the diaphragm contracts, thus enlarging the thoracic cavity and reducing intra-thoracic pressure (the external intercostals muscles also participate in this enlargement). When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity in conjunction with the abdominal muscle which act as the antagonist pair to diaphragm's contraction Antagonist (muscle). The diaphragm is also found in other vertebrates such as reptiles. It is responsible for all the breathing related to voice. The diaphragm also helps to expel vomit, feces, and urine from the body by increasing intra-abdominal pressure. A hiatal hernia can result from a tear or weakness in the diaphragm near the gastroesophageal junction.

If the diaphragm is struck, or otherwise spasms, breathing will become difficult. This is called having the wind knocked out of you.
hiccup occurs when the diaphragm contracts periodically without voluntary control. Diaphragmatic injuries result from either blunt or penetrating trauma. The Diaphragm is a dome-shaped musculofibrous septum which separates the thoracic from the abdominal cavity, its convex upper surface forming the floor of the former, and its concave under surface the roof of the latter. Its peripheral part consists of muscular fibers which take origin from the circumference of the thoracic outlet and converge to be inserted into a central tendon. The muscular fibers may be grouped according to their origins into three parts: ORIGIN-sternal=two fleshy slips from the back of the xiphoid process. Costal=the inner surfaces of the cartilages and adjacent portions of the lower six ribs on either side, interdigitating with the Transversus abdominis. Lumbar=aponeurotic arches, named the lumbocostal arches, and from the lumbar vertebrae by two pillars or crura. There are two lumbocostal arches, a medial and a lateral, on either side. [edit] Crura and central tendon At their origins the crura are tendinous in structure, and blend with the anterior longitudinal ligament of the vertebral column. The central tendon of the diaphragm is a thin but strong aponeurosis situated near the center of the vault formed by the muscle, but somewhat closer to the front than to the back of the thorax, so that the posterior muscular fibers are the longer. [edit] Openings in the Diaphragm The diaphragm is pierced by a series of apertures to permit of the passage of structures between the thorax and abdomen. Three large openings—the aortic, the esophageal, and the vena cava—and a series of smaller ones are described. caval opening=T8=inferior vena cava, and some branches of the right phrenic nerve.  esophageal hiatus=T10=esophagus, the vagus nerves, and some small esophageal arteries. aortic hiatus=T12=the aorta, the azygos vein, and the thoracic duct. two lesser aperture of right crus=greater and lesser right splanchnic nerves. three lesser aperture of left crus=greater and lesser left splanchnic nerves and the hemiazygos vein. behind the diaphragm, under the medial lumbocostal arches= gangliated trunks of the sympathetic. areolar tissue between the sternal and costal parts (see also foramina of Morgagni)= the superior epigastric branch of the internal mammary artery and some lymphatics from the abdominal wall and convex surface of the liver. areolar tissue between the fibers springing from the medial and lateral lumbocostal arches= This interval is less constant; when this interval exists, the upper and back part of the kidney is separated from the pleura by areolar tissue only. Variations

The sternal portion of the muscle is sometimes wanting and more rarely defects occur in the lateral part of the central tendon or adjoining muscle fibers.


The dermis is a layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many nerve endings that provide the sense of touch and heat. It contains the hair follicles, sweat glands, sebaceous glands, apocrine glands and blood vessels. The blood vessels in the dermis provide nourishment and waste removal to its own cells as well as the Stratum basale of the epidermis.

Dorsal root ganglion

In anatomy and neurology, the dorsal root ganglion (or spinal ganglion) is a nodule on a dorsal root that contains cell bodies of neurons in afferent spinal nerves. All of the axons in the dorsal root convey somatosensory information, bringing sensory information into the brain and spinal cord. These neurons are of the pseudo-unipolar type, meaning they have two axons, one that conveys sensory information from the body to the soma of the neuron and one from the soma to the junction in the dorsal horn of the spinal cord.

The dorsal root ganglia lie along the vertebral columna by the spine.


Conducting outward from a part or organ; specifically: conveying nervous impulses to an effector (muscles organs). Conveys nerve impulses from the brain and spinal cord to effectors that may be either muscles or glands.

Epidermis (skin)

Epidermis is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface and is made up of stratified squamous epithelium with an underlying basal lamina. Components The epidermis contains no blood vessels, and is nourished by diffusion from the dermis. The main type of cells which make up the epidermis are keratinocytes, melanocytes, Langerhans cells and Merkels cells. [edit] Layers The epidermis is divided into several layers where cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate and become filled with keratin. They eventually reach the top layer called stratum corneum and become sloughed off, or desquamated. This process is called keratinization and takes place within weeks. The outermost layer of epidermis consists of 25 to 30 layers of dead cells. [edit] Sublayers Epidermis is divided into the following 5 sublayers or strata, listed from the superficial to deep: Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum germinativum (also called "stratum basale") Mnemonics used for remembering the layers of the skin (using "stratum basale" instead of "stratum germinativum"): "Corn Lovers Grow Several Bales" (from superficial to deep) "Before Signing, Get Legal Counsel" (from deep to superficial)


In biology and medicine, epithelium is a tissue composed of a layer of cells. Epithelium lines both the outside (skin) and the inside cavities and lumen of bodies. The outermost layer of our skin is composed of dead stratified squamous, keratinized epithelial cells. Mucous membranes lining the inside of the mouth, the esophagus, and part of the rectum are lined by nonkeratinized stratified squamous epithelium. Other, open to outside body cavities are lined by simple squamous or columnar epithelial cells. Other epithelial cells line the insides of the lungs, the gastrointestinal tract, the reproductive and urinary tracts, and make up the exocrine and endocrine glands. Functions of epithelial cells include secretion, absorption, protection, transcellular transport, sensation detection, and selective permeability. Endothelium (the inner lining of blood vessels, the heart, and lymphatic vessels) is a specialized form of epithelium. Another type, Mesothelium, forms the walls of the pericardium, pleurae, and peritoneum. In humans, epithelium is classified as a primary body tissue, the other ones being connective tissue, muscle tissue and nervous tissue. Squamous: Squamous cells are flat cells with an irregular flattened shape. A one-cell layer of simple squamous epithelium forms the alveoli of the respiratory membrane, and the endothelium of capillaries, and is a minimal barrier to diffusion. Other places where squamous cells can be found include the filtration tubules of the kidneys, and the major cavities of the body. These cells are relatively inactive metabolically, and are associated with the diffusion of water, electrolytes, and other substances. Cuboidal: As the name suggests, these cells have a shape similar to a cube, meaning its width is the same size as its height. The nuclei of these cells are usually located in the center. Columnar: These cells are taller than they are wide. Simple columnar epithelium is made up of a single layer of cells that are longer than they are wide. The nucleus is also closer to the base of the cell. The small intestine is a tubular organ lined with this type of tissue. Unicellular glands called goblet cells are scattered throughout the simple columnar epithelial cells and secrete mucus. The free surface of the columnar cell has tiny hairlike projections called microvilli. They increase the surface area for absorption. Transitional: This is a specialized type of epithelium found lining organs that can stretch, such as the urothelium that lines the bladder and ureter of mammals. Since the cells can slide over each other, the appearance of this epithelium depends on whether the organ is distended or contracted: if distended, it appears as if there are only a few layers; when contracted, it appears as if there are several layers.


The esophagus (Fig. 1032) or gullet is a muscular canal, about 23 to 25 cm. long, extending from the pharynx to the stomach. It begins in the neck at the lower border of the cricoid cartilage, opposite the sixth cervical vertebra, descends along the front of the vertebral column, through the superior and posterior mediastina, passes through the diaphragm, and, entering the abdomen, ends at the cardiac orifice of the stomach, opposite the eleventh thoracic vertebra.


Provide information about the external environment. They are sensitive to stimuli outside the body and transmit sensations of hearing, sight, smell, taste, touch, pressure, temperature, and pain. Exteroceptors are located at or near the surface of the body.

Falciform Ligament (Liver) (This demonstrates the falciform lig superior attachment to the diaphragm.

The superior surface is attached to the diaphragm and anterior abdominal wall by a triangular or falciform fold of peritoneum, the falciform ligament, in the free margin of which is a rounded cord, the ligamentum teres (obliterated umbilical vein). The line of attachment of the falciform ligament divides the liver into two parts, termed the right and left lobes, the right being much the larger.


In anatomy, a ganglion (pl. ganglia) is a tissue mass, which is composed mainly of somata and dendritic structures, which often interconnect with each other to form a complex system of ganglia known as a plexus. These structures provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems.

There are two major groups of ganglia: dorsal root ganglia (also known as the spinal ganglia) and autonomic ganglia. The former contains the cell bodies of sensory (afferent) nerves and the latter contains the cell bodies of autonomic nerves. In the autonomic nervous system, fibers from the central nervous system to the ganglion are known as preganglionic fibers, while those from the ganglion to the effector organ are called postganglionic fibers.

Gastroesophageal Reflux Disease (GERD)

Gastroesophageal Reflux Disease (GERD; or GORD when spelling œsophageal, the BrE form) is defined as chronic symptoms or mucosal damage produced by the abnormal reflux of gastric contents into the esophagus[1]. This is commonly due to transient or permanent changes in the barrier between the esophagus and the stomach. This can be due to incompetence of the lower esophageal sphincter (LES), transient LES relaxation, impaired expulsion of gastric reflux from the esophagus, or a hiatal hernia. Adults Heartburn is the major symptom of acid in the esophagus, characterized by burning discomfort behind the breastbone (sternum). Findings in GERD include esophagitis (reflux esophagitis) — inflammatory changes in the esophageal lining (mucosa) — strictures, difficulty swallowing (dysphagia), and chronic chest pain. Patients may have only one of those findings. Typical GERD symptoms include cough, hoarseness, voice changes, chronic ear ache, burning chest pains, nausea or sinusitis. GERD complications include stricture formation, Barrett's esophagus, esophageal ulcers, and possibly even lead to esophageal cancer, especially in adults over 60 years old. Occasional heartburn is common but does not necessarily mean one has GERD. Patients with heartburn symptoms more than once a week are at risk of developing GERD. A hiatal hernia is usually asymptomatic, but the presence of a hiatal hernia is a risk factor for developing GERD.[edit]

Generator Potential

Generator Potentials differ from nerve action potentials in several ways. A generator potential is a localized response that decreases in intensity as it travels along a nerve fiber, whereas a nerve action potential is propagated at a constant and maximum strength. A generator potential is a graded response, that is within limits, the stronger and more frequent the stimulus, the greater the magnitude of the generator potential. A nerve action potential obeys the all-or-none principal. A generator potential usually lasts longer than 1 to 2 msec, a nerve action potential does not. A generator potential does not have a refractory period, whereas a nerve action potential has one that lasts for about 1 msec. This means  that if a second stimulus is applied to a receptor before a generator potential resulting from the first stimulus disappears, the second stimulus can add to the effect of the first, producing an even greater generator potential. Hus, summation in producting generator potentials is possible, but summation of nerve action potentials is not. The generator potential only travels a few millimeters before dying out. When a generator potential reashes threshold, it initiates a nerve action potential. The function of a generator potential is to convert a stimulus into a nerve action potential.

Golgi tendon organ

The Golgi organ (also called Golgi tendon organ, neurotendinous organ or neurotendinous spindle), is a proprioceptive sensory receptor organ that is located at the insertion of skeletal muscle fibres into the tendons of skeletal muscle. The Golgi organ should not be confused with the Golgi Apparatus, which is an organelle in the eukaryotic cell, or the Golgi stain, which is an histologic stain for neuron cell bodies. Anatomy The body of the organ is made up of strands of collagen that are connected at one end to the muscle fibers and at the other merge into the tendon proper. Each tendon organ is innervated by a single type Ib sensory afferent fiber that branches and terminates as spiral endings around the collagen strands. The Ib afferent axon is a large diameter, myelinated axon. Each neurotendinous spindle is enclosed in a fibrous capsule which contains a number of enlarged tendon fasciculi (intrafusal fasciculi). One or more nerve fibres perforate the side of the capsule and lose their medullary sheaths; the axis-cylinders subdivide and end between the tendon fibers in irregular disks or varicosities (see figure). [edit] Function During muscle contraction the strands of collagen are stretched as the muscle shortens. This stretching deforms the terminals of the Ib afferent axon, opening stretch-sensitive cation channels. As a result, the axon is depolarized and fires nerve impulses up to the central nervous system via the spinal cord. The action potential frequency signals the force being developed within the muscle. This sensory feedback plays an important role in spinal reflexes and in the central control of muscle contraction. Specifically, it is postulated that because a Golgi tendon organ exists in serial connection with muscle fibers, it can measure the tension that each muscle contraction builds up. The Ib afferent axon synapses with interneurons within the spinal cord and also relays information to the brain. One of the main spinal reflexes receiving an input from the Ib afferent is the autogenic inhibition reflex, which is involved with the regulation of the force profile of on-going muscle contractions.

The ascending or afferent pathways to the cerebellum are the dorsal and ventral spinocerebellar tracts and are involved in the cerebellar regulation of movement. [edit] History It was once believed that Golgi tendon organs were responsible for the clasp-knife reflex observed in spinal cord-injured patients. This theory has been rejected in favor of one that explains the reflex with free nerve endings.

The Golgi tendon organs are located in the tendon close to the musculotendinous junction. A few to many muscle fibers are attached to each Golgi tendon organ, with an average of 10-15. The Golgi tendon organ is  ituated in series with the muscle, whereas the neuromus­cular spindle is parallel to the muscle. The neuromuscular spindle monitors the length of the muscle, while the Golgi tendon organ monitors the tension of the muscle. Stimulation of the Golgi tendon organ is from contraction of the muscle, with stronger stimulation from greater contraction. The Golgi tendon organ inhibits the muscle with which it is associated. The tendon receptors have afferent nerve supply of the large group I. The neuron is similar to the group I afferent of the neuromuscular spindle and is differentiated as being Ib, while the neuromuscular spindle nerve is la. Transmission from the Golgi tendon organ goes to both local areas in the cord and through the spinal cerebellar tracks into the cerebellum. The local signal excites interneurons which in turn inhibit the anterior alpha motor neuron of its own muscle and synergists, while facilitating antagonists. The inhibitory nature of the Golgi tendon organ acts as a protective mechanism for the muscle. Many muscles have much greater strength potential than the structure can withstand. A failure of muscle control can cause possible avulsion or tearing of the muscle itself. Stimulation to the Golgi tendon’ organ inhibits the muscle from going past its structural capabilities. An example of the effectiveness of the Golgi tendon apparatus is observing individuals arm-wrestling. The loser generally gives out completely - all at once - when impulses from the Golgi tendon organ overpower the alpha motor neuron impulses and shut the muscle down. It is observed, however, that many trained weight-lifters apparently have learned to mentally override the Golgi tendon mechanism to provide a greater amount of strength potential. This can, of course, be structurally damaging to the body, as in the situation when an arm wrestler fractures the humerus.

There is evidence that the Golgi tendon organ, like the muscle spindle cell, can dysfunction, giving improper communication to the cord level and higher centers. This can cause the muscle with which it is directly associated to be either hypotonic or hypertonic, or to possibly influence other remote muscles. .As on the neuromuscular spindle cell, the influence of manual manipulation of the Golgi tendon can be observed by influencing normally functioning Golgi tendon organs. The only difficulty in performing this experiment is in applying the manipulative force at the correct location. It requires excellent palpatory skills to find where the Golgi tendon organ is probably located, and a certain amount of luck that the receptor is actually there. This is necessary because a normal Golgi tendon organ will not therapy localize, revealing its location. To cause a strong muscle to weaken in a normal subject, digital pressure is applied over the probable location of the Golgi tendon organ in alignment with the muscle fibers away from the belly of the muscle. If the attempt is successful, there will be an immediate dramatic weakening of the muscle which will last from approximately a half-minute to several minutes. In attempting this experiment, a muscle should be selected which does not have an extensive amount of tendon surface area, and the muscle should have adequate strength so that it is not easily overpowered. A good muscle to use is the rectus femoris of the quadriceps group. The entire quadriceps group is more difficult for. achieving successful weakening because of the large area of origin of the muscles.


Homeopathy (also homœopathy or homoeopathy; from the Greek, μοιος, hómoios, "similar" + πάθος, páthos, "suffering" or "disease") is a controversial form of alternative medicine that aims to treat "like with like". Substances that cause symptoms similar to the disease in large quantities are heavily diluted, with shaking at each stage of the dilution. Homeopaths contend that the shaking causes some imprint (or memory) of the diluted substance, despite the fact that at many common homeopathic dilutions, no molecules of the original substance are likely to remain.[1] Homeopathy is based on a vitalist world view, which sees the underlying causes of sickness as imbalances in a hypothetical vital force. Proponents claim that homeopathic treatment can harmonize and re-balance the vital force in the body, so restoring health. This claim is unsupported by modern biology or medicine.[2][3][4][5][6] Homeopathy traces its origins to the late 18th century when it was founded by German physician Samuel Hahnemann, who noted some similarity of the symptoms of undiluted cinchona bark in healthy individuals with those of malaria, which it is used to treat. Hahnemann decided that an effective drug must produce the symptoms in healthy individuals that are similar to the symptoms of the sick patient which they are supposed to be treating.[7] Based on later experiments, Hahnemann reasoned that using natural doses of substances would generally not help patients because, if they produced effects similar to those of the disease, they would only make symptoms worse, and thus proposed the dilution of substances in water or alcohol, with shaking (known as "succussion") after each dilution, in order to try and imprint the liquid with the memory of the original substance. To account for homeopathic remedies sometimes failing to produce lasting cures of long-standing chronic diseases, Hahnemann proposed that the vital force in the body has the ability to react or adapt to disturbances, referred to as the "law of susceptibility", and that various causes can attract hypothetical disease-causing entities called "miasms", which he claimed could produce symptoms of disease within the body, and formed a deeper, harder to treat cause of illness.[7] The medical efficacy of homeopathic treatments is unconfirmed by scientific and clinical studies.[8][9][10] The hypothesis that extreme dilution makes any drug more powerful is antithetical to the principles of chemistry and physics as well as the observed dose-response relationships of conventional medicines. The scientific community asserts there is no scientific evidence supporting the contention that water or alcohol retain any memory of a substance. Researchers conclude that any positive effects of homeopathic treatment are simply a placebo effect.[6][11][8][9] Homeopaths are also often accused of giving 'false hope' to patients who might be better advised to seek effective conventional treatments. Studies have shown homeopaths frequently advise patients to avoid standard medical procedures including drugs which can prevent diseases such as malaria.[12][13] The meta-analyses that have been done on homeopathy have confirmed that its effects are unlikely to be beyond that of placebo, and those studies that have shown positive results for homeopathic treatments were flawed in design. These findings, along with the proscription by homeopaths against conventional medicine and their encouragement of a "holistic" approach to health, are in keeping with the conclusion of many scientists that homeopathy is a sort of quackery.[14][15][16]


Humanism[1][2] is a broad category of ethical philosophies that affirm the dignity and worth of all people, based on the ability to determine right and wrong by appeal to universal human qualities—particularly rationality. It is a component of a variety of more specific philosophical systems, and is incorporated into several religious schools of thought. Humanism entails a commitment to the search for truth and morality through human means in support of human interests. In focusing on the capacity for self-determination, Humanism rejects the validity of transcendental justifications, such as a dependence on faith, the supernatural, or allegedly divinely revealed texts. Humanists endorse universal morality based on the commonality of the human condition, suggesting that solutions to human social and cultural problems cannot be parochial.[3]

Inferior vena cava

The inferior vena cava (or IVC) is the large vein that carries de-oxygenated blood from the lower half of the body into the heart. It is posterior to the abdominal cavity and runs along side of the vertebral column on its right side (i.e. it is a retroperitoneal structure). It enters the right atrium at the lower right, back side of the heart. The IVC is formed by the joining of the left and right common iliac veins and brings blood into the right atrium of the heart. It also anastomoses with the azygos vein system (which runs on the right side of the vertebral column) and the venous plexuses next to the spinal cord. Because the IVC is not centrally located, there are some asymmetries in drainage patterns. The gonadal veins and suprarenal veins drain into the IVC on the right side, but into the renal vein on the left side, which in turn drains into the IVC. By contrast, all the lumbar veins and hepatic veins usually drain directly into the IVC. Note that the vein that carries de-oxygenated blood from the upper half of the body is the superior vena cava.


The act of passing from one proposition, statement, or judgment considered as true to another whose truth is believed to follow from that of the former. the act of passing from statistical sample data to generalizations (as of the value of population parameters) usually with calculated degrees of certainty.

Lateral arcuate ligament

The lateral arcuate ligament (also lateral lumbocostal arch) is a ligament under the diaphragm that arches across the upper part of the quadratus lumborum. [edit] Structure The lateral arcuate ligament runs from the front of the transverse process of the first lumbar vertebra, and, laterally, to the tip and lower margin of the twelfth rib. It forms an arch over the quadratus lumborum muscle. [edit] See also Medial arcuate ligament Median arcuate ligament

Life coaching

Life coaching is a practice of assisting clients to determine and achieve personal goals. A coach will use a variety of methods, tailored to the client, to move through the process of setting and reaching goals. Coaching is not targeted at psychological illness, and coaches are not therapists (although therapists may become coaches). [edit] Origins and History With roots in executive coaching, which itself drew on techniques developed in management consulting and leadership training, life coaching also draws from a wide range of disciplines, including sociology, psychology, postive adult development, career counseling, mentoring, and numerous other types of counseling. The coach applies mentoring, values assessment, behavior modification, behavior modeling, goal-setting, and other techniques in assisting clients. Coaches are to be distinguished from counselors, whether counselors in psychotherapy or other careers. Writing for the International Journal of Coaching in Organizations, Patrick Williams states: It is helpful to understand that both coaching and therapy have the same roots. Coaching evolved from three main streams that have flowed together: 1. The helping professions such as psychotherapy and counseling.  2. Business consulting and organizational development.  3. Personal development training, such as EST, Landmark Education, Tony Robbins, Stephen Covey seminars, Eric Edmeades, and others. [1] Williams further states that the movement towards Client-centered therapy in the 1940s and 1950s by psychologists Carl Rogers and Abraham Maslow helped shift the emphasis in therapy towards the client becoming an active agent in their progress and growth. He credits Maslow's 1968 treatise “Toward a Psychology of Being” with providing the framework for modern life coaching as it is practiced today.

Longitudinal study

A longitudinal study is a correlational research study that involves repeated observations of the same items over long periods of time, often many decades. Longitudinal studies are often used in psychology to study developmental trends across the life span. The reason for this is that unlike cross-sectional studies, longitudinal studies track the same people, and therefore the differences observed in those people are less likely to be the result of cultural differences across generations. Longitudinal studies are also used in medicine to uncover predictors of certain diseases.


Detect mechanical deformation of the receptor itself or in adjacent cells. Stimuli so detected include those related to touch, pressure, vibration, Proprioception, hearing, equilibrium and blood pressure. A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. There are four main types in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles. There are also mechanoreceptors in the hairy skin, and the hair cells in the cochlea are the most sensitive mechanoreceptors in tranducing air pressure waves into sound. Mechanism of sensation Mechanoreceptors are primary neurons that respond to mechanical stimuli by firing action potentials. Peripheral transduction is believed to occur in the end-organs. In sensory transduction, the afferent neurons transmit the message through a synapse in the dorsal column nuclei, where another neuron sends the signal to the thalamus, where another neuron sends the signal to the somatosensory cortex. [edit] Feedback More recent work has expanded the role of the mechanoreceptors for feedback in fine motor control. Single action potentials from RAI and PC afferents are directly linked to activation of related hand muscles,[1] whereas SAI activation does not trigger muscle activity. [edit] History The human work stemmed from Vallbo and Johansson's percutaneous recordings from human volunteers in the late 1970s. Work in rhesus monkeys has found virtually identical mechanoreceptors with the exception of Ruffini corpuscles which are not found in the monkey. [edit] Types There are two ways to categorize mechanoreceptors; by what kind of sensation they perceive and by the rate of adaption. [edit] By sensation Cutaneous mechanoreceptors provide the senses of touch, pressure, vibration, proprioception and others. The SAI type mechanoreceptor, with the Merkel cell end-organ, underlies the perception of form and roughness on the skin.[2]  The RAI type mechanoreceptor underlies the perception of flutter,[3] and slip on the skin.[4] Pacinian receptors underlie the perception of high frequency vibration.[5] SAII mechanoreceptors respond to skin stretch, but have not been closely linked to either proprioceptive or mechanoreceptive roles in perception.[6]

[edit] By rate of adaption Mechanoreceptors can also be separated into categories based on their rates of adaptivity. When a mechanoreceptor receives a stimulus it begins to fire impulses or action potentials at an elevated frequency (the stronger the stimulus the higher the frequency). The cell, however, will soon “adapt” to a constant or static stimulus and the pulses will subside to a normal rate. Receptors that adapt quickly (i.e. quickly return to a normal pulse rate) are referred to as ‘’phasic’’. Those receptors that are slow to return to their normal firing rate are called ‘’tonic’’. Phasic mechanoreceptors are useful in sensing such things as texture, vibrations, etc; whereas tonic receptors are useful for temperature and proprioception among others. Slowly adapting type I mechanoreceptors have multiple Merkel corpuscle end-organs. Slowly adapting type II mechanoreceptors have single Ruffini corpuscle end-organs. Rapidly adapting type I mechanoreceptors have multiple Meissner corpuscle end-organs. Rapidly adapting type II mechanoreceptors (usually called Pacinian) have single Pacinian corpuscle end-organs. [edit] Receptive field Cutaneous mechanoreceptors with small, accurate receptive fields are found in areas needing accurate taction (e.g. the fingertips). In the fingertips and lips, innervation density of slowly adapting type 1 and rapidly adapting type 1 mechanoreceptors are greatly increased. These two types of mechanoreceptors have small discrete receptive fields and are thought to underly most low threshold use of the fingers in assessing texture, surface slip, and flutter. Mechanoreceptors found in areas of the body with less tactile acuity tend to have larger receptive fields.

Medial arcuate ligament

The medial arcuate ligament (also medial lumbocostal arch) is tendinous fascia that arches over the psoas major muscle as it passes through the diaphragm. [edit] Structure The medial arcuate ligament is an arch in the fascia covering the upper part of the psoas major. It is attached to the side of the body of the first or second lumbar vertebra; laterally, it is fixed to the front of the transverse process of the first and, sometimes also, to that of the second lumbar vertebra. It lies between the lateral arcuate ligament and the midline median arcuate ligament. [edit] See also Lateral arcuate ligament Median arcuate ligament

Median arcuate ligament

The median arcuate ligament is a ligament under the diaphragm that connects the right and left crura of diaphragm. [edit] Structure The median arcuate ligament is formed by the right and left crura of the diaphragm. The crura connect to form an arch, behind which is the aortic hiatus. [edit] See also Medial arcuate ligament Lateral arcuate ligament

Mediastinal pleura

Different portions of the parietal pleura have received special names which indicate their position: thus, that portion which lines the inner surfaces of the ribs and Intercostales is the costal pleura; that clothing the convex surface of the diaphragm is the diaphragmatic pleura; that which rises into the neck, over the summit of the lung, is the cupula of the pleura (cervical pleura); and that which is applied to the other thoracic viscera is the mediastinal pleura.


The mediastinum is a non-delineated group of structures in the thorax (chest), surrounded by loose connective tissue. It is the central compartment of the thoracic cavity. It contains the heart, the great vessels of the heart, esophagus, trachea, thymus, and lymph nodes of the central chest. The mediastinum lies between the right and left pleuræ in and near the median sagittal plane of the chest. It extends from the sternum in front to the vertebral column behind, and contains all the thoracic viscera except the lungs. It may be divided for purposes of description into two parts: an upper portion, above the upper level of the pericardium, which is named the superior mediastinum; and a lower portion, below the upper level of the pericardium. This lower portion is again subdivided into three parts, viz.: that in front of the pericardium, the anterior mediastinum; that containing the pericardium and its contents, the middle mediastinum; and that behind the pericardium, the posterior mediastinum. It is surrounded by the chest wall anteriorly, the lungs laterally and the spine posteriorly. It is continuous with the loose connective tissue of the neck, and extends inferiorly onto the diaphragm. Note that clinical radiologists and anatomists categorize the mediastinum in slightly different ways. [edit] Role in disease Main article: mediastinal tumor

The mediastinum frequently is the site of involvement of various tumors. Mediastinitis is inflammation of the tissues in the mediastinum, usually bacterial and due to rupture of organs in the mediastinum. As the infection can progress very quickly, this is a serious condition. Pneumomediastinum is the presence of air in the mediastinum, which can lead to pneumothorax, pneumoperitoneum, and pneumopericardium if left untreated in some cases. However, that does not always happen and sometimes those conditions actually are the cause, not the result, of pneumomediastinum. These two conditions frequently accompany Boerhaave's syndrome, or spontaneous esophageal rupture.

Membrane potential

Membrane potential (or transmembrane potential or transmembrane potential difference or transmembrane potential gradient), is the electrical potential difference (voltage) across a cell's plasma membrane. The plasma membrane bounds the cell to provide a stable environment for biological processes. Membrane potential arises from the action of ion transporters embedded in the membrane which maintain viable ion concentrations inside the cell. The term "membrane potential" is sometimes used interchangeably with cell potential but is applicable to any lipid bilayer or membrane. The membrane potential of most cells is kept relatively stable. Unlike most cells, neurons are specialized to use changes in membrane potential for fast communication, primarily with other neurons. When a neuron fires, the action potential travels down the axon to the synapses: the magnitude of the axonal membrane potential varies dynamically along its length. On reaching a (chemical) synapse, a neurotransmitter is released causing a localized change in potential in the membrane of the target neuron by opening ion channels in its membrane.


The meninges (singular meninx) is the system of membranes which envelop the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.


Mesentery is, in anatomy, the double layer of peritoneum that connects a part of the small intestine to the posterior wall of the abdomen. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.


The mesothelium is a membrane that forms the lining of several body cavities: the pleura (thoracal cavity), peritoneum (abdominal cavity) and pericardium (heart sac). Mesothelial tissue also surrounds the male internal reproductive organs (the tunica vaginalis testis) and covers the internal reproductive organs of women (the tunica serosa uteri). Mesothelium that covers the internal organs is called visceral mesothelium, while the layer that covers the body walls is called the parietal mesothelium. Mesothelium derives from the embryonic mesoderm cell layer, that lines the coelom (body cavity) in the embryo. It develops into the layer of cells that covers and protects most of the internal organs of the body. The mesothelium forms a monolayer of flattened squamous-like epithelial cells resting on a thin basement membrane supported by connective tissue. Cuboidal mesothelial cells may be found at areas of injury, the milky spots of the omentum, and the peritoneal side of the diaphragm overlaying the lymphatic lacunae. The luminal surface is covered with microvilli. The proteins and serosal fluid trapped by the microvilli provide a frictionless surface for internal organs to slide past one another. The mesothelium is composed of an extensive monolayer of specialized cells (mesothelial cells) that line the body's serous cavities (cavities formed by a Serous membrane) and internal organs. The main purpose of these cells is to produce a lubricating fluid that is released between layers, providing a slippery, non-adhesive and protective surface to facilitate intracoelomic movement. The mesothelium is also implicated in the transport and movement of fluid and particulate matter across the serosal cavities, leucocyte migration in response to inflammatory mediators, synthesis of pro-inflammatory cytokines, growth factors and extracellular matrix proteins to aid in serosal repair, and the release of factors to promote the disposition and clearance of fibrin (such as plasminogen). It is an antigen presenting cell. Furthermore, the secretion of glycosaminoglycans and lubricants may protect the body against infection and tumor dissemination.


a division of philosophy that is concerned with the fundamental nature of reality and being and that includes ontology, cosmology, and often epistemology abstract philosophical studies : a study of what is outside objective experience. Metaphysics is the branch of philosophy concerned with explaining the ultimate nature of reality, being, and the world. Its name derives from the Greek words μετά (metá) (meaning "after") and φυσικά (physiká) (meaning "after talking about physics"), "physics" referring to those works on matter by Aristotle in antiquity.[2] Many philosophers such as Immanuel Kant would later argue that certain questions concerning metaphysics (notably those surrounding the existence of God, soul and freedom) are inherent to human nature and have always intrigued mankind.

Metaphysics is the branch of philosophy that investigates principles of reality transcending those of any particular science, traditionally including cosmology and ontology. It is also concerned with explaining the ultimate nature of being and the world.[1] Its name derives from the Greek words μετά (metá) (meaning "after") and φυσικά (physiká) (meaning "after talking about physics"), "physics" referring to those works on matter by Aristotle in antiquity.[2] In english, though, "meta" means "beyond;over;transcending". Therefore, metaphysics is the study of that which transcends physics. Many philosophers such as Immanuel Kant would later argue that certain questions concerning metaphysics (notably those surrounding the existence of God, soul and freedom) are inherent to human nature and have always intrigued mankind. Some examples are: What is the nature of reality? Why does the world exist, and what is its origin or source of creation? Does the world exist outside the mind? If things exist, what is their objective nature? A central branch of metaphysics is ontology, the investigation into what types of things there are in the world and what relations these things bear to one another. The metaphysician also attempts to clarify the notions by which people understand the world, including existence, objecthood, property, space, time, causality, and possibility. More recently, the term "metaphysics" has also been used more loosely to refer to "subjects that are beyond the physical world". A "metaphysical bookstore", for instance, is not one that sells books on ontology, but rather one that sells books on spirits, faith healing, crystal power, occultism, and other such topics. Before the development of modern science, scientific questions were addressed as a part of metaphysics known as "natural philosophy"; the term "science" itself meant "knowledge". The Scientific Revolution, however, made natural philosophy an empirical and experimental activity unlike the rest of philosophy, and by the end of the eighteenth century it had begun to be called "science" in order to distinguish it from philosophy. Metaphysics therefore became the philosophical enquiry into subjects beyond the physical world. Natural philosophy and science may still be considered topics of metaphysics, if the definition of "metaphysics" includes empirical explanations.

Muscle spindles

Muscle structure is innervated by both sensory and motor neuron axons. Its functions are to send proprioceptive information about the muscle to the central nervous system, and to respond to muscle stretching. Anatomy Muscle spindles are found within the fleshy portions of muscles, embedded in so-called extrafusal muscle fibres. They are composed of 3-10 intrafusal muscle fibres, of which there are three types: dynamic nuclear bag fibres (bag1 fibres) static nuclear bag fibers (bag2 fibres) nuclear chain fibers and the axons (are dendrites but some authors call axions because of their similarity pseudo-unipolar type) of sensory neurons. Axons of motor neurons also terminate in muscle spindles; they make synapses at either or both of the ends of the intrafusal muscle fibers and regulate spindle sensitivity. Muscle spindles are encapsulated by connective tissue, and are aligned parallel to extrafusal muscle fibers, unlike Golgi tendon organs, which are oriented in series. The muscle spindle has both sensory and motor components. Primary and secondary sensory fibers spiral around and terminate on the central portions of intrafusal fibers, providing the sensory component of the structure via stretch-sensitive ion-channels of the axons. In humans, the motor component is provided by gamma motoneurons; in many other species, beta motoneurons innervate the spindles. They cause a slight contraction of the end portions of the intrafusal muscle fibers when activated. The gamma (fusimotor) axons only innervate the intrafusal muscle fibres, whereas the beta (skeletofusimotor) axons innervate both extrafusal and ntrafusal muscle fibres. These motorneurons are classified as static or dynamic according to their pattern of innervation and their physiological effects. The static axons innervate the chain or bag2 fibres. The dynamic axons innervate the bag1 fibres and increase the velocity sensitivity of the Ia afferents. [edit] Sensitivity Modification The function of the gamma motor neuron neuromuscular junction is not to supplement the general muscle contraction provided by extrafusal fibers, but to modify the sensitivity of the muscle spindle to stretch. Upon release of acetylcholine by the gamma neuron, the end portions of the intrafusal muscle fibers (fusiform=tapering toward each end. Spindle) contract, thus deliberately elongating the non-contractile central portions of intrafusal muscle fibers. This opens stretch-sensitive ion channels of the centrally-positioned sensory axons, leading to an influx of sodium ions. This raises the resting potential of these axons, thereby increasing the probability of action potential firing, thus increasing the sensitivity of the muscle spindle.[edit] Stretch reflex When a muscle is stretched, primary sensory fibers (Group Ia afferent neurons) of the muscle spindle respond to both the velocity and the degree of stretch, and send this information to the spinal cord. Likewise, secondary sensory fibers (Group II afferent neurons) detect and send information about the degree of stretch (but not the velocity thereof) to the CNS. This information is transmitted monosynaptically to an alpha efferent motor fiber, which activates extrafusal fibers of the muscle to contract, thereby reducing stretch, and polysynaptically through an interneuron to another alpha motoneuron, which inhibits contraction in the antagonizing muscles. PNF stretching, or proprioceptive neuromuscular facilitation, is a method of flexibility training that reduces the automatic reflex action in order allow muscles to lengthen. [edit] Development It is also believed that muscle spindles play a critical role in sensorimotor development.

The 3-10 intrafusal muscle fibers (cells) are partially enclosed in connective tissue capsule which is filled with lymph. The ends of the spindles are anchored to the endomysium and perimysium. This means that as the extrafusal muscle fibers are stretched or contracted so are the intrafusal muscle fibers. The spindles, intrafusal muscle fibers (cells) are 10 to 25% smaller than the extrafusal fibers. These intrafusal fibers measure around 2-20 mm and they are microscopic. That is they may be just under an inch long but they are microscopically wide. As per above the end portions of the intrafusal fibers contract (they contain actin and myosin myofilaments which are the contractile elements of a muscle cell) while the center portion do not contract. Although the center portion of the intrafusal fiber does not contain contractile elements it does contain multiple cellular nuclei. The central portion of the intrafusal fibers is called the nuclear bag because it is bag like. There are 3-9 nuclear chain fibers and 1 to 3 nuclear bag fibers with two types of nuclear bag fibers dynamic and static. There are 3-9 nuclear chain fibers per muscle spindle that are half the size of the nuclear bag fibers. Their nuclei are aligned in a chain and they excite the secondary nerve. They are static while the nuclear bag fibers are dynamic in comparison. The name "nuclear chain" refers to the structure of the central region of the fiber, where the sensory axons wrap around the intrafusal fibers. As intrafusal muscle fibers, nuclear chain fibers both send afferent innvervation and receive efferent innervation. The afferent innervation is via Group II and Ia neurons. These project to the nucleus proprius in the dorsal horn of the spinal cord. Efferent innervation is via static γ neurons. Stimulation of γ neurons causes the nuclear chain to shorten along with the extrafusal muscle fibers. This shortening allows the nuclear chain fiber to be sensitive to changes in length while its corresponding muscle is flexed. As aforementioned, the intrafusal fibers are innervated by both motor and sensory neurons.

The extrafusal skeletal muscle fibers receive efferent (motor) neurons from the ventral horn of the gray matter in the spinal cord or motor nuclei of the cranial nerves. These are approximate 70% of the motor fibers to the muscle and are large fibers, classified as alpha motor neurons. The balance (30%) are gamma motor neurons which give efferent supply to the intrafusal fibers of the neuromuscular spindle. The central portion (called the nuclear bag) of the intrafusal fibers has either no or few actin and myosin filaments, and consequently does not contract. It is here that the sensory receptor area is located. It is supplied by two types of afferent nerves-one, type 1a which is located around the nuclear bag, and usually two of the type II fibers in the contractile part of the intrafusal fibers. The 1a fiber is large and has a high velocity of conduction, while the type II fiber is significantly slower. The primary (1a) attaches by curling around the central portion of the intrafusal fiber. The secondary (II) afferent fibers are interdigitating with the Myofibers.

There are two types of response which take place when the muscle spindle is stretched. There is a prolonged response referred to a tonic, which takes place for several minutes, from the stretched stimulation of the secondary receptors. This is roughly interpreted by the spinal cord as the magnitude of change. The primary receptors also have a similar response but are Phasic, having a much greater response while the muscle is actually lengthening. As soon as the movement stops, the impulse decreases dramatically. This is interpreted as the rate of change by the spinal cord. When the receptor area shortens, there is a decrease in the impulse output from the primary afferent. As soon as the shortening ceases, the impulses re-appear.

Any change of tension on the receptor portion of the intrafusal muscle fiber of the neuromuscular spindle causes an appraisal of the change to be sent over the afferent pathway. The change on the receptor area can be from contraction or elongation of the extrafusal muscle fibers, which in turn shortens or elongates the intrafusal muscle fibers. This takes place from stretching the muscle or contraction caused by stimulation of the alpha motor neurons. On the other hand, the receptor area can be stimulated from gamma nerve stimulation, causing the intrafusal muscle fibers to contract, thus stimulating the receptor area of the neuromuscular spindle cell. In effect, the muscle spindle acts as a comparator of the lengths of the two types of muscle fibers. There are normally sensory nerve impulses coming from the neuromuscular spindle all the time. Changing the length of the muscle either increases or decreases the rate of firing of the afferent nerve.

The stretch reflex is divided into two types. The dynamic stretch reflex occurs when a quick stretching of the muscle causes the neuromuscular spindle to be stimulated, and the monosynaptic reflex arc causes the same muscle to contract. An example of this is the knee jerk reflex. The static stretch reflex is from stimulation of the neuromuscular spindle from a slow and continued stretch of the muscle, causing a less intense reaction which causes the muscle to have an opposing contraction to the lengthening force.

The neuromuscular spindle controls smoothness of muscle contraction so that it does not oscillate and jerk in its motions. This correlates with the Phasic muscles having a higher percentage of neuromuscular spindles than the tonic weight bearing muscles of the body. The Phasic muscles need more control because of their more intricate, dynamic capabilities. Regulation of muscle force is also needed to hold varying weights at specific heights. As additional weight is put on the extended arm, the neuromuscular spindle cell monitors the increasing weight and regulates the contracting force desired.

The neuromuscular spindle cell is responsible for the organization of the agonist with the antagonist, synergists and fixator muscles. There is an excitatory effect on the muscle in which the spindle lies, facilitory effect on the synergistic and fixator muscles, and an inhibitory effect upon the antagonist muscles.

The effect of the neuromuscular spindle cell on the extrafusal fibers may become either hyperactive or hyperactive and cause erroneous information to be transferred through the simple oligosynaptic (olig=few) loops into the neuronal pools affecting this or other muscles. It is unknown histologically what causes the neuromuscular spindle to malfunction. It could be injury to the spindle fibers, or trauma to the capsule of the spindle causing swelling of the spindle, with consequent mechanical pressures on the receptor area. It could also be a lack of gliding motion of the intrafusal fibers by an adhesion with the fibrous capsule, which is normally separated from the intrafusal capsules by a lymph space bridged by delicate septa. The changes in the proprioceptors could also be a trained or learned response, as is seen in proprioceptive neuromuscular facilitation, an example of which is the conditioning a weight lifter does for greater power.

Muscle tone

Muscle tone (aka residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles. It helps maintain posture and declines during REM sleep. Note that muscular tone is not defined as muscular shaping or the aspect of general Human physical appearance. Purpose Unconscious nerve impulses maintain the muscles in a partially contracted state. If a sudden pull or stretch occurs, the body responds by automatically increasing the muscle's tension, a reflex which helps guard against danger as well as helping to maintain balance. The presence of near-continuous innervation makes it clear that tonus describes a "default" or "steady state" condition. There is, for the most part, no actual "rest state" insofar as activation is concerned.

In terms of skeletal muscle, both the extensor muscle and flexor muscle use the term tonus to refer to the "at rest" or normal enervation that maintains current positions of bones.

Cardiac muscle and smooth muscle, although not directly connected to the skeleton also have tonus in the sense that although their contractions are not matched with those of antagonist muscles, their non-contractive state is characterized by (sometimes random) enervation. [edit] Pathological tonus Physical disorders can result in abnormally low (hypotonia) or high (hypertonia) muscle tone. Another form of hypertonia is Paratonia, which is associated with dementia. [edit] Tonus in surgery In ophthalmology, tonus may be a central consideration in eye surgery, as in the manipulation of extraocular muscles to repair strabismus. Tonicity aberrations are associated with many diseases of the eye (e.g. Adie syndrome). [edit] Tonus training Some[Cite] present the idea that constant daily resistance training, or training at high intensities, will increase one's muscle tone, as the neurological system becomes more tense after constant exertion to stay in a state of greater readiness for the tension.


Neuroscience is a scientific discipline that studies the structure, function, development, genetics, biochemistry, physiology, pharmacology, and pathology of the nervous system. Traditionally it is seen as a branch of biological sciences. However, recently there has been a convergence of interest from many allied disciplines, including psychology, computer science, statistics, physics, philosophy, mathematics, and medicine. The scope of neuroscience has now broadened to include any systematic scientific experimental and theoretical investigation of the central and peripheral nervous system of biological organisms. The methodologies employed by neuroscientists have been enormously expanded, from biochemical and genetic analysis of dynamics of individual nerve cells and their molecular constituents to imaging representations of perceptual and motor tasks in the brain. Furthermore, neuroscience is at the frontier of investigation of the brain and mind. The study of the brain is becoming the cornerstone in understanding how we perceive and interact with the external world and, in particular, how human experience and human biology influence each other. It is likely that the study of the brain will become one of the central intellectual endeavors in the coming decades. The scientific study of the nervous systems underwent a significant increase in the second half of the twentieth century, principally due to revolutions in molecular biology, neural networks and computational neuroscience. It has become possible to understand, in exquisite detail, the complex processes occurring inside a single neuron and in a network that eventually produces the intellectual behavior, cognition, emotion and physiological responses. The task of neural science is to explain behavior in terms of the activities of the brain. How does the brain marshal its millions of individual nerve cells to produce behavior, and how are these cells influenced by the environment...? The last frontier of the biological sciences--their ultimate challenge--is to understand the biological basis of consciousness and the mental processes by which we perceive, act, learn, and remember. — Eric Kandel, Principles of Neural science, fourth edition


A nerve is an enclosed, cable-like bundle of axons (the long, slender projection of a neuron). Neurons are sometimes called nerve cells, though this term is technically imprecise since many neurons do not form nerves, and nerves also include the glial cells that ensheath the axons in myelin. Nerves are part of the peripheral nervous system. Afferent nerves convey sensory signals to the central nervous system, for example from skin or organs, while efferent nerves conduct stimulatory signals from the central nervous system to the muscles and glands. Afferent and efferent nerves are often arranged together, forming mixed nerves. Each peripheral nerve is covered externally by a dense sheath of connective tissue, the epineurium. Underlying this is a layer of flat cells forming a complete sleeve, the perineurium. Perineurial septa extend into the nerve and subdivide it into several bundles of fibres. Surrounding each such fibre is the endoneurial sheath. This is a tube which extends, unbroken, from the surface of the spinal cord to the level at which the axon synapses with its muscle fibres or ends in sensory endings. The endoneurial sheath consists of an inner sleeve of material called the glycocalyx and an outer, delicate, meshwork of collagen fibres. Peripheral nerves are richly supplied with blood. Most nerves connect to the central nervous system through the spinal cord. The twelve cranial nerves, however, connect directly to parts of the brain. Spinal nerves are given letter-number combinations according to the vertebra through which they connect to the spinal column. Cranial nerves are assigned numbers, usually expressed as Roman numerals from I to XII. In addition, most nerves and major branches of nerves have descriptive names. Inside the central nervous system, bundles of axons are termed tracts rather than nerves. The signals that nerves carry, sometimes called nerve impulses, are also known as action potentials: rapidly (up to 120 m/s) traveling electrical waves, which begin typically in the cell body of a neuron and propagate rapidly down the axon to its tip or "terminus." The signals cross over from the terminus to the adjacent neurotransmitter receptor through a gap called the synapse. Motor neurons innervate or activate muscles groups. The nerve system runs through the spinal cord. [edit] Clinical importance Damage to nerves can be caused by physical injury, swelling (e.g. carpal tunnel syndrome), autoimmune diseases (e.g. Guillain-Barré syndrome), infection (neuritis), diabetes, or failure of the blood vessels surrounding the nerve. Pinched nerves occur when pressure is placed on a nerve, usually from swelling due to an injury or pregnancy. Nerve damage or pinched nerves are usually accompanied by pain, numbness, weakness, or paralysis. Patients may feel these symptoms in areas far from the actual site of damage, a phenomenon called referred pain. Referred pain occurs because when a nerve is damaged, signaling is defective from all parts of the area which the nerve receives input, not just the site of the damage. Neurologists usually diagnose disorders of the nerves by a physical examination, including the testing of reflexes, walking and other directed movements, muscle weakness, proprioception, and the sense of touch. This initial exam can be followed with tests such as nerve conduction study and electromyography (EMG).


Detect pain, usually as a result of physical or chemical damage to tissues. A nociceptor is a sensory receptor that sends signals that cause the perception of pain in response to potentially damaging stimulus. Nociceptors are the nerve endings responsible for nociception, one of the two types of persistent pain (the other, neuropathic pain, occurs when nerves in the central or peripheral nervous system are not functioning properly). When they are activated, nociceptors can trigger a reflex. Location Nociceptors are sensory neurons that are found in external tissues such as skin, cornea and mucosa as well as in internal organs, such as the muscle, joint, bladder and gut. The cell bodies of these neurons are located in either the dorsal root ganglia or the trigeminal ganglia. [edit] Types and functions There are several types of nociceptors and they are classified according to the stimulus modalities to which they respond: i.e. thermal, mechanical or chemical. Some nociceptors respond to more than one of these modalities and are consequently designated polymodal. Other nociceptors respond to none of these modalities (although they may respond to stimulation under conditions of inflammation) and have thereby earned the more poetic title of sleeping or silent nociceptors (Kandel et al, 2000). Thermal nociceptors are activated by noxious heat or cold, temperatures above 45°C and below 5°C (Kandel et al, 2000). Mechanical nociceptors respond to excess pressure or mechanical deformation. Polymodal nociceptors respond to damaging stimuli of a chemical, thermal, or mechanical nature (Kandel et al, 2000). Nociceptors may have either Aδ fiber axons or more slowly conducting C fiber axons. Thus, pain often comes in two phases, the first mediated by the fast-conducting Aδ fibers and the second part due to C fibers. Silent nociceptors do not usually fire action potentials, though they are much more likely to do so in the presence of inflammation or damaging chemicals (Kandel et al, 2000). Together these nociceptors allow the organism to feel pain in response to damaging pressure, excessive heat, excessive cold and a range of chemicals, the majority of which are damaging to the tissue surrounding the nociceptor. [edit] Pathway Afferent nociceptive fibers (those that send information to, rather than from the brain) travel back to the spinal cord where they form synapses in its dorsal horn. The cells in the dorsal horn are divided into physiologically distinct layers called laminae. Different fiber types form synapses in different layers. Aδ fibers form synapses in laminae I and V, C fibers connect with neurons in lamina II, Aβ fibers connect with lamina IV. Information is then sent from the spinal cord to the thalamus and the cerebral cortex in the brain.


In philosophy, ontology (from the Greek ν, genitive ντος: of being (part. of εναι: to be) and -λογία: science, study, theory) is the study of being or existence and forms the basic subject matter of metaphysics. It seeks to describe or posit the basic categories and relationships of being or existence to define entities and types of entities within its framework. Ontology can be said to study conceptions of reality; and, for the sake of distinction, at least to the extent to which its counterpart, epistemology can be represented as being a search for answers to the questions "What do you know?" and "How do you know it?", ontology can be represented as a search for an answer to the question "What is the nature of the knowable things?". Some philosophers, notably of the Platonic school, contend that all nouns refer to entities. Other philosophers contend that some nouns do not name entities but provide a kind of shorthand way of referring to a collection (of either objects or events). In this latter view, mind, instead of referring to an entity, refers to a collection of mental events experienced by a person; society refers to a collection of persons with some shared interactions, and geometry refers to a collection of a specific kind of intellectual activity. Any ontology must give an account of which words refer to entities, which do not, why, and what categories result. When one applies this process to nouns such as electrons, energy, contract, happiness, time, truth, causality, and God, ontology becomes fundamental to many branches of philosophy.[1]


Osteoarthritis / Osteoarthrosis (OA, also known as degenerative arthritis, degenerative joint disease, arthrosis or in more colloquial terms "wear and tear"), is a condition in which low-grade inflammation results in pain in the joints, caused by wearing of the cartilage that covers and acts as a cushion inside joints. As the bone surfaces become less well protected by cartilage, the patient experiences pain upon weight bearing, including walking and standing. Due to decreased movement because of the pain, regional muscles may atrophy, and ligaments may become more lax. OA is the most common form of arthritis. The word is derived from the Greek word "osteo", meaning "of the bone", "arthro", meaning "joint", and "itis", meaning inflammation, although many sufferers have little or no inflammation. OA affects nearly 21 million people in the United States, accounting for 25% of visits to primary care physicians, and half of all NSAID (Non-Steroidal Anti-Inflammatory Drugs) prescriptions. It is estimated that 80% of the population will have radiographic evidence of OA by age 65, although only 60% of those will be symptomatic.[1] Treatment is with NSAIDs, local injections of glucocorticoid or hyaluronan, and in severe cases, with joint replacement surgery. There has been no cure for OA, as cartilage has not been induced to regenerate. However, if OA is caused by cartilage damage (for example as a result of an injury) Autologous Chondrocyte Implantation may be a possible treatment.[2] Clinical trials employing tissue-engineering methods have demonstrated regeneration of cartilage in damaged knees, including those that had progressed to osteoarthritis.[3] Further, in January 2007, Johns Hopkins University was offering to license a technology of this kind, [4] listing several clinical competitors in its market analysis.

Pacinian corpuscle

Pacinian corpuscles are one of the four major types of mechanoreceptor, responsible for sensitivity to deep pressure touch and high frequency vibration. Location These corpuscles are found in mesenteries, especially the pancreas, and are often found near joints. Like Ruffini endings, they are found in deep subcutaneous tissue, and are considered rapidly adapting receptors, which means they will not fire action potentials throughout the duration of a stimulus but, rather, will fire briefly at its beginning and end (Kandel et al., 2000). [edit] Structure Similar in physiology to the Meissner's corpuscle, Pacinian corpuscles are larger and fewer in number than both Merkel cells and Meissner's corpuscles (Kandel et al., 2000). The Pacinian corpuscle is ovoid shaped and approximately 1 mm in length. The entire corpuscle is wrapped by a layer of connective tissue. It has 20 to 60 concentric lamellae composed of fibrous connective tissue and fibroblasts, separated by gelatinous material. The lamellae are very thin, flat, modified Schwann cells. In the center of the corpuscle is the inner bulb, a fluid-filled cavity with a single afferent unmyelinated nerve ending. [edit] Function Pacinian corpuscles detect gross pressure changes and vibrations. Any deformation in the corpuscle causes action potentials to be generated, by opening pressure-sensitive sodium ion channels in the axon membrane. This allows sodium ions to influx in, creating a receptor potential. These corpuscles are especially susceptible to vibrations, which they can sense even centimeters away (Kandel et al., 2000). Pacinian corpuscles cause action potentials when the skin is rapidly indented but not when the pressure is steady, due to the layers of connective tissue that cover the nerve ending (Kandel et al., 2000). It is thought that they respond to high velocity changes in joint position. Pacinian corpuscles have a large receptive field on the skin's surface with an especially sensitive center (Kandel et al., 2000). They only sense stimuli that occur within this field.


Philosophical and theoretical framework of a scientific school or discipline within which theories, laws, and generalizations and the experiments performed in support of them are formulated; broadly : a philosophical or theoretical framework of any kind

Parasympathetic nervous system

The parasympathetic nervous system (PSNS) is one of three divisions of the autonomic nervous system (ANS). The ANS -a subdivision of the peripheral nervous system (PNS)- is subdivided into the sympathetic (SNS), parasympathetic (PSNS) and enteric (bowels) nervous system (ENS). Sympathetic and parasympathetic divisions typically function in opposition to each other. But this opposition is better termed complementary in nature rather than antagonistic. For an analogy, one may think of the sympathetic division as the accelerator and the parasympathetic division as the brake. The sympathetic division typically functions in actions requiring quick responses. The parasympathetic division functions with actions that do not require immediate reaction.

The parasympathetic nervous system is a portion of the visceral (autonomic) branch of the PNS (peripheral nervous system). The regions of the body associated with this division are the cranial and sacral regions of the spinal cord. Specifically, cranial nerves III, VII, IX, X (vagus n.) and in the sacral region (spinal nerves exiting from the sacrum) the spinal nerves S2 to S4.

Similar to the sympathetic division, the parasympathetic division also has pre- and post- ganglionic neurons. Typically, in the parasympathetic division the ganglion will be closer to the area of innervation - unlike the sympathetic ganglion which form immediately lateral and inferior to the spinal nerve - making up the so called "chain ganglion".


Detect light on the retina of the eye

Phrenic ganglion

Located near the celiac plexus, below the diaphragm, stomach, liver. Located more below the stomach on the left side of the body. See phrenic plexus

Phrenic nerve

The phrenic nerve arises from the third, fourth, and fifth cervical spinal nerves (C3-C5) in humans. It arises from the fifth, sixth and seventh cervical spinal nerves (C5-7) in most domestic animals. The phrenic nerve is made up mostly of motor nerve fibres for producing contractions of the diaphragm. In addition, it provides sensory innervation for many components of the mediastinum and pleura, as well as the upper abdomen, especially the liver and gall bladder.  Both phrenic nerves run from C3, C4 and C5 along the anterior scalene muscle deep to the carotid sheath. The right phrenic nerve passes over the right brachiocephalic artery, posterior to the subclavian vein, and then crosses the root of the right lung and then leaves the thorax by passing through the vena cava hiatus opening in the diaphragm at the level of T8. The right phrenic nerve passes over the right atrium. The left phrenic nerve passes over the left ventricle and pierces the diaphragm separately. Both these nerves supply motor fibres to the diaphragm and sensory fibres to the fibrous pericardium, mediastinal pleura and diaphragmatic peritoneum.

The pericardiacophrenic artery and vein(s) travel with the phrenic nerve. Pain arising from structures served by the phrenic nerve is often "referred" to other somatic regions served by spinal nerves C3-C5. For example, a subphrenic abscess (beneath the diaphragm) might cause a patient to feel pain in the right shoulder. Irritation of the phrenic nerve (or the tissues supplied by it) leads to the hiccup reflex. A hiccup is a spasmodic contraction of the diaphram, which pulls air against the closed folds of the larynx. The phrenic nerve must be identified during thoracic surgery and preserved. It passes anterior to the hilum of the corresponding lung, and therefore can be identified easily. Severing the phrenic nerve will paralyse that half of the diaphragm. Breathing will be made more difficult but will continue provided the other nerve is intact.

Phrenic plexus

From these illustrations, especially 848 it is clear that the phrenic plexus is separate from the phrenic ganglion, as is the celiac plexus from the celiac ganglion although some of these structures are not well defined. See phrenic ganglion  More centrally located below the liver near the celiac plexus. The phrenic plexus (plexus phrenicus) accompanies the inferior phrenic artery to the diaphragm, some filaments passing to the suprarenal gland. It arises from the upper part of the celiac ganglion, and is larger on the right than on the left side. It receives one or two branches from the phrenic nerve. At the point of junction of the right phrenic plexus with the phrenic nerve is a small ganglion (ganglion phrenicum). This plexus distributes branches to the inferior vena cava, and to the suprarenal and hepatic plexuses.

Pleural cavity (See Pulmonary pleura Pleura)

The lungs are surrounded by two membranes, the pleurae. The outer pleura is attached to the chest wall and is known as the parietal pleura; the inner one is attached to the lung and other visceral tissues and is known as the visceral pleura. In between the two is an actual thin space known as the pleural cavity or pleural space. It is filled with pleural fluid, a serous fluid produced by the pleura. A normal 70 kg human has approximately 12-15 mL of pleural fluid. Pleural fluid serves several functions. It lubricates the pleural surfaces and allows the pleural layers to slide against each other easily during respiration. Pleural fluid also provides the surface tension that keeps the lung surface in close apposition with the chest wall. This allows optimal inflation of alveoli during respiration. It also directly transmits pressures from the chest wall to the visceral pleural surface (and hence, the lung). Therefore, movements of the chest wall during breathing are coupled closely to movements of the lungs. The parietal pleura is highly sensitive to pain; the visceral pleura is not. The visceral pleura has a dual blood supply from the bronchial and pulmonary arteries. In normal pleurae, most fluid is produced by the parietal circulation (intercostal arteries) via bulk flow and reabsorbed by the lymphatic system. Thus, pleural fluid is continuously produced and reabsorbed. The rate of reabsorption may increase up to 40x before significant amounts of fluid accumulate within the pleural space. In humans, there is no anatomical connection between the left and right pleural cavities, so in cases of pneumothorax (see below), the other hemithorax will still be able to function normally.

Pulmonary pleura (See Pleural cavity Pleura)

Each lung is invested by an exceedingly delicate serous membrane, the pleura, which is arranged in the form of a closed invaginated sac. A portion of the serous membrane covers the surface of the lung and dips into the fissures between its lobes; it is called the pulmonary pleura (or visceral pleura). The visceral pleura is attached directly to the lungs. Visceral pleura is the innermost of the two layer of pleural membranes investing the lungs. It consists of a smooth layer of continuous mesothelial cells. It is deep to the parietal pleura (fibrous connective tissue); a thin layer of serous fluid intervenes between the two in the potential space of the pleural cavity. The visceral and parietal pleura only merge together as a layer at root of the lung. Elsewhere, the fluid lubricant within the pleural cavity permits both layers to slide freely over each other. The visceral pleura closely follows the underlying lung surface. It passes down into fissures between lobes; along these fissures, visceral pleura is apposed to visceral pleura.


The pericardium is a double-walled sac that contains the heart and the roots of the great vessels. There are two layers to this sac: the fibrous pericardium and the serous pericardium. The serous pericardium, in turn, is divided into two layers; in between these two layers there is a potential space called the pericardial cavity. The fibrous pericardium is the most superficial layer. It is a dense connective tissue, protecting the heart, anchoring it to the surrounding walls, and preventing it from overfilling with blood. It is continuous with the outer adventitial layer (adventitial) of the neighboring great blood vessels. The serous pericardium is deeper than the fibrous pericardium. It contains two layers, both of which function in lubricating the heart to prevent friction from occurring during heart activity. The layer next to the fibrous pericardium is the parietal layer. The layer deep to the fibrous pericardium is the visceral layer. When this layer comes into contact with the heart (not the great vessels), it is known as the epicardium. Together these two layers form a continuous uninterrupted membrane. Between these two layers exists a small cavity called the pericardial cavity, which contains a supply of serous fluid.The serous fluid that is found in this space is known as the pericardial fluid.


In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdominal cavity - it covers most of the intra-abdominal organs. It is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum both supports the abdominal organs and serves as a conduit for their blood and lymph vessels and nerves. Although they ultimately form one continuous sheet, two types or layers of peritoneum and a potential space between them are referenced: The outer layer, called the parietal peritoneum, is attached to the abdominal wall. The inner layer, the visceral peritoneum, is wrapped around the internal organs that are located inside the abdominal cavity. The potential space between these two layers is the peritoneal cavity; it is filled with a small amount (about 50 ml) of slippery serous fluid that allows the two layers to slide freely over each other. The term mesentery is often used to refer to a double layer of visceral peritoneum. There are often blood vessels, nerves, and other structures between these layers. It should be noted that the space between these two layers is technically outside of the peritoneal sac, and thus not in the peritoneal cavity. There are two main regions of the peritoneum, connected by the epiploic foramen: the greater sac (or general cavity of the abdomen), represented in red in the diagrams above. the lesser sac (or omental bursa), represented in blue. The lesser sac is divided into two "omenta": The lesser omentum (or gastrohepatic) is attached to the lesser curvature of the stomach and the liver. The greater omentum (or gastrocolic) hangs from the greater curve of the stomach and loops down in front of the intestines before curving back upwards to attach to the transverse colon. In effect it is draped in front of the intestines like an apron and may serve as an insulating or protective layer. The mesentery is the part of the peritoneum through which most abdominal organs are attached to the abdominal wall and supplied with blood and lymph vessels and nerves.

Phrenic plexus

The phrenic plexus accompanies the inferior phrenic artery to the diaphragm, some filaments passing to the suprarenal gland. It arises from the upper part of the celiac ganglion, and is larger on the right than on the left side. It receives one or two branches from the phrenic nerve. At the point of junction of the right phrenic plexus with the phrenic nerve is a small ganglion (ganglion phrenicum). This plexus distributes branches to the inferior vena cava, and to the suprarenal and hepatic plexuses.


Physics (Greek: φύσις (phúsis), "nature" and φυσικ (phusiké), "knowledge of nature") is the branch of science concerned with discovering and characterizing universal laws that govern matter, energy, space, and time. Discoveries in physics resonate throughout the natural sciences, and physics has been described as the "fundamental science" because other fields such as chemistry and biology investigate systems whose properties depend on the laws of physics.[1] The emergence of physics as a science distinct from natural philosophy began with the scientific revolution of the 16th and 17th centuries, and continued through the dawn of modern physics in the early 20th century. The field has continued to expand, with a growing body of research leading to discoveries such as the Standard Model of fundamental particles and a detailed history of the universe, along with revolutionary new technologies like nuclear energy and semiconductors. Research today progresses on a vast array of topics, including high-temperature superconductivity, quantum computing, the search for the Higgs boson, and the attempt to develop a theory of quantum gravity. Grounded in observations and experiments and supported by deep, far-reaching theories, physics has made a multitude of contributions to science, technology, and philosophy.


A placebo is a preparation which is pharmacologically inert but which may have a medical effect based solely on the power of suggestion, a response known as the placebo effect or placebo response. It may be administered through ingestion, injection, inhalation, insertion into a body cavity, or applied topically.[1] The term placebo effect (as distinct from the more correct term placebo response) was introduced by T. C. Graves in 1920 "because it is the subject that has the subject-centred response. It is not the administered substance that generates the observed effect." Sometimes known as non-specific effects or subject-expectancy effects, a so-called placebo effect occurs when a patient's symptoms are altered in some way (i.e., alleviated or exacerbated) by an otherwise inert treatment, due to the individual expecting or believing that it will work. Some people consider this to be a remarkable aspect of human physiology; others consider it to be an illusion arising from the way medical experiments are conducted.


Placebo Analgesia

Careful studies have shown that the placebo effect can alleviate pain, although the effect is more pronounced with pre-existing pain than with experimentally induced pain. People can be conditioned to expect analgesia in certain situations. When those conditions are provided to the patient, the brain responds by generating a pattern of neural activity that produces objectively quantifiable analgesia. (Benedetti 2003, Wager 2004) Evans argued that the placebo effect works through a suppression of the acute phase response, and as a result does not work in medical conditions that do not feature this. (Evans 2005) The acute phase response consists of inflammation and sickness behaviour: Four classic signs of ‘inflammation’: tumor, rubor, calor, and dolor – (Latin for "swelling, redness, heat, and pain").

Sickness behaviour: lethargy, apathy, loss of appetite, and increased sensitivity to pain.



The lungs are surrounded by two membranes, the pleurae. The outer pleura is attached to the chest wall and is known as the parietal pleura; the inner one is attached to the lung and other visceral tissues and is known as the visceral pleura. In between the two is an actual thin space known as the pleural cavity or pleural space. It is filled with pleural fluid, a serous fluid (serous membrane) produced by the pleura. A normal 70 kg human has approximately 12-15 mL of pleural fluid. Pleural fluid serves several functions. It lubricates the pleural surfaces and allows the pleural layers to slide against each other easily during respiration. Pleural fluid also provides the surface tension that keeps the lung surface in close apposition with the chest wall. This allows optimal inflation of alveoli during respiration. It also directly transmits pressures from the chest wall to the visceral pleural surface (and hence, the lung). Therefore, movements of the chest wall during breathing are coupled closely to movements of the lungs. The parietal pleura is highly sensitive to pain; the visceral pleura is not. The visceral pleura has a dual blood supply from the bronchial and pulmonary arteries. In normal pleurae, most fluid is produced by the parietal circulation (intercostal arteries) via bulk flow and reabsorbed by the lymphatic system. Thus, pleural fluid is continuously produced and reabsorbed. The rate of reabsorption may increase up to 40x before significant amounts of fluid accumulate within the pleural space. In humans, there is no anatomical connection between the left and right pleural cavities, so in cases of pneumothorax (see below), the other hemithorax will still be able to function normally.




In many animals the processes of neurons join together to form a plexus or nerve net. This is the characteristic form of nervous system in the coelenterates and persists with modifications in the flatworms. The nerves of the radially symmetric echinoderms also take this form, where a plexus underlies the ectoderm of these animals and deeper in the body other nerve cells form plexuses of limited extent.

In vertebrates nerves branch and rejoin in some parts of the body, for example the brachial plexus made up of the spinal nerves which enter the arm and the solar plexus above the stomach.

Almost a hundred such plexuses have been named in the human body, but the four primary nerve plexuses are the cervical plexus, brachial plexus, lumbar plexus, and the sacral plexus.


Posterior horn


The posterior horn (posterior column, posterior cornu, dorsal horn, spinal dorsal horn) of the spinal cord is the dorsal (more towards the back) grey matter of the spinal cord. It receives several types of sensory information from the body, including light touch, proprioception, and vibration. This information is sent from receptors of the skin, bones, and joints through sensory neurons whose cell bodies lie in the dorsal root ganglion.


Pseudoscience  [35]


Pseudoscience is any body of knowledge, methodology, belief, or practice that claims to be scientific or is made to appear scientific, but does not adhere to the basic requirements of the scientific method. The term pseudoscience is based on the Greek root pseudo- (false or pretending) and science (derived from Latin scientia, meaning knowledge). The first recorded use was in 1843 by French physiologist François Magendie considered a pioneer in experimental physiology. The term has negative connotations, because it is used to indicate that subjects so labeled are inaccurately or deceptively portrayed as science. Accordingly, those labeled as practicing or advocating a "pseudoscience" normally reject this classification. As it is taught in certain introductory science classes, pseudoscience is any subject that appears superficially to be scientific or whose proponents state is scientific but nevertheless contravenes the testability requirement, or substantially deviates from other fundamental aspects of the scientific method.  Professor Paul DeHart Hurd  argued that a large part of gaining scientific literacy is being able to distinguish science from pseudo-science such as astrology, eugenics, quackery, the occult, and superstition.[9] Certain introductory survey classes in science take careful pains to delineate the objections scientists and skeptics have to practices that make direct claims contradicted by the scientific discipline in question. Beyond the initial introductory analyses offered in science classes, there is some epistemological disagreement about whether it is possible to distinguish "science" from "pseudoscience" in a reliable and objective way. Pseudoscience’s may be characterized by the use of vague, exaggerated or untestable claims, over-reliance on confirmation rather than refutation, lack of openness to testing by other experts, and a lack of progress in theory development.


Using the accurate findings of scientific inquiry to draw unsupported false conclusions and or conversely claims or appears to be scientific without adhering to the scientific method.





Provide information about body position and movement. Such sensations give us information about muscle tension, the position and activity of our joints, and equilibrium. These receptors are located in muscles, tendons, joints, and the internal ear.


Proprioception (PRO-pree-o-SEP-shun (IPA pronunciation: [ˈpɹopɹiːoˌsɛpʃən]); from Latin proprius, meaning "one's own" and perception) is the sense of the relative position of neighbouring parts of the body. Unlike the six exteroceptive senses (sight, taste, smell, touch, hearing, and balance) by which we perceive the outside world, and interoceptive senses, by which we perceive the pain and the stretching of internal organs, proprioception is a third distinct sensory modality that provides feedback solely on the status of the body internally. It is the sense that indicates whether the body is moving with required effort, as well as where the various parts of the body are located in relation to each other. The Position-Movement sensation was originally described in 1557 by Julius Caesar Scaliger as a 'sense of locomotion'. Much later in 1826 Charles Bell expounded the idea of a 'muscle sense' and this is credited with being one of the first physiologic feedback mechanisms. Bell's idea was that commands were being carried from the brain to the muscles, and that reports on the muscle's condition would be sent in the reverse direction. Later, in 1880, Henry Charlton Bastian suggested 'kinaesthesia' instead of 'muscle sense' on the basis that some of the afferent information (back to the brain) was coming from other structures including tendon, joints, skin, and muscle. In 1889, Alfred Goldscheider suggested a classification of kinaesthesia into 3 types: muscle, tendon, and articular sensitivity. In 1906, Sherrington published a landmark work which introduced the terms 'proprioception' 'interoception', and 'exteroception'. The 'exteroceptors' being the organs responsible for information from outside the body such as the eyes, ears, mouth, and skin. The interoceptors then gave information about the internal organs, while 'proprioception' was awareness of movement derived from muscular, tendon, and articular sources. Such a system of classification has kept physiologists and anatomists searching for specialised nerve endings which transmit data on joint capsule and muscle tension (such as muscle spindles and Pacini corpuscles).


Receptor Potential


A phenomenon that has many characteristics similar to a generator potential is called a receptor potential. When a receptor cell connected to a neuron via a synapse is adequately stimulated, the receptor responds by depolarization of its membrane. This depolarization is called a receptor potential. Once developed, a receptor potential stimulates the release of neurotransmitters from a receptor cell, which alters the permeability of the neuron’s membrane. If the neuron becomes depolarized to threshold, a nerve action potential is triggered.


Rene Descartes (1596-1650)


French Mathematician and philosopher-established the necessity for a rigorous, rational analysis and explanation of natural phenomena)(used inference (the act of passing from one proposition, statement, or judgment considered as true to another whose truth is believed to follow from that of the former)) [36] [37] [38] “I think, therefore I am””there is nothing which gives me assurance of their truth beyond this; that I see very clearly that in order to think it is necessary to exist.”

René Descartes (French IPA: [ʁə'ne de'kaʁt]) (March 31, 1596 – February 11, 1650), also known as Renatus Cartesius (latinized form), was a highly influential French philosopher, mathematician, scientist, and writer. Dubbed the "Father of Modern Philosophy," and the "Father of Modern Mathematics," much of subsequent western philosophy is a reaction to his writings, which have been closely studied from his time down to the present day. His influence in mathematics is also apparent, the Cartesian coordinate system that is used in plane geometry and algebra being named for him, and he was one of the key figures in the Scientific Revolution.


Right atrium


The right atrium (in older texts termed the "right auricle") is one of four chambers (two atria and two ventricles) in the human heart. It receives de-oxygenated blood from the superior and inferior vena cavae and the coronary sinus, and pumps it into the right ventricle through the tricuspid valve. The sinoatrial node (SAN) is located within this chamber next to the vena cava. This is a group of pacemaker cells which spontaneously depolarise to create an Action Potential. The cardiac action potential then spreads across both atria causing them to contract forcing the blood they hold into their corresponding ventricles. In early life, when a fetus is in the womb, the right atrium has a hole within its septum through to the left atrium, this makes them continuous with each other which is essential for foetal circulation. This junction is called the “Foramen Ovale”. Once born (usually within a year's time) the Foreman Ovale seals over and it is renamed as the “Fossa Ovalis”. The Fossa Ovalis is seen as an embryonic remnant. The right atrium also holds the coronary sinus which is the opening of the vein that drains the myocardium itself. Attached to the right atrium is the right auricular appendix.



Righting Reflexes


righting reflexes [39] [40] [41] [42] [43] [44] [45] [46] [47]


The ability to assume an optimal position when there has been a departure from it) (facilitated by equilibrium Proprioceptors).



Got an idea for how nature works and want to find out if it is real and true. Use scientific method to find out-formulate testable hypotheses, test these hypotheses under controlled conditions, Put together those hypotheses that are correct to formulate theories. Inductive reasoning formulates these hypothesis only after empirical observation and deductive reasoning begins with testable hypothesis and looks to experiment for conformation. Alexander follows an incomplete path (unscientific) he formulates theories (Paradigm) based on anecdotal experience (uncontrolled-no objective empirical observation) and or makes subjective (uncontrolled-non objective) observations to theories. This process runs the risk that imagination exceeds reality and you will see what you want to see. It may be a successful strategy since suggestion can produce healing and the marketplace may reward the visionary even if they are wrong about the details. When the vision is appealing to consumer it is rewarded financially. (?)

Scientific Method

Scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. It is based on gathering observable, empirical and measurable evidence subject to specific principles of reasoning,[1] the collection of data through observation and experimentation, and the formulation and testing of hypotheses.[2]

Although procedures vary from one field of inquiry to another, identifiable features distinguish scientific inquiry from other methodologies of knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies to test these hypotheses. These steps must be repeatable in order to predict dependably any future results. Theories that encompass wider domains of inquiry may bind many hypotheses together in a coherent structure. This in turn may help form new hypotheses or place groups of hypotheses into context.

Among other facets shared by the various fields of inquiry is the conviction that the process must be objective to reduce a biased interpretation of the results. Another basic expectation is to document, archive and share all data and methodology so it is available for careful scrutiny by other scientists, thereby allowing other researchers the opportunity to verify results by attempting to reproduce them. This practice, called full disclosure, also allows statistical measures of the reliability of these data to be established.

Serous membrane

In anatomy, a serous membrane, or serosa, is a smooth membrane (Example= Pulmonary pleura) consisting of a thin layer of cells which excrete a fluid, known as serous fluid. Serous membranes line and enclose several body cavities, known as serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement. Serosa is not to be confused with adventitia, a connective tissue layer which binds together structures rather than reducing friction between them. Each serous membrane is composed of a secretory epithelial layer and a connective tissue layer underneath. The epithelial layer, known as mesothelium, consists of a single layer of avascular flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid. This fluid has a consistency similar to thin mucous. These cells are bound tightly to the underlying connective tissue. The connective tissue layer provides the blood vessels and nerves for the overlying secretory cells, and also serves as the binding layer which allows the whole serous membrane to adhere to organs and other structures.

Sigmund Freud (1856-1939)

Sigmund Freud (IPA: [ˈziːkmʊnt ˈfʁɔʏt]), born Sigismund Schlomo Freud (May 6, 1856 – September 23, 1939), was an Austrian neurologist and psychiatrist who co-founded the psychoanalytic school of psychology. Freud is best known for his theories of the unconscious mind, especially involving the mechanism of repression; his redefinition of sexual desire as mobile and directed towards a wide variety of objects; and his therapeutic techniques, especially his understanding of transference in the therapeutic relationship and the presumed value of dreams as sources of insight into unconscious desires.[citation needed] He is commonly referred to as "the father of psychoanalysis" and his work has been highly influential — popularizing such notions as the unconscious, defense mechanisms, Freudian slips and dream symbolism — while also making a long-lasting impact on fields as diverse as literature, film, Marxist and feminist theories, philosophy, and psychology. However, his theories remain controversial and disputed by numerous critics.

Smooth muscle

Muscle tissue that lacks cross striations, is made up of elongated spindle-shaped cells having a central nucleus, and is found especially in vertebrate hollow organs and structures (as the digestive tract and bladder) as thin sheets performing functions not subject to direct voluntary control and in all or most of the musculature of invertebrates other than arthropods. Smooth muscle is a type of non-striated muscle, found within the "walls" of hollow organs and elsewhere like the bladder and abdominal cavity, the uterus, male and female reproductive tracts, the gastrointestinal tract, the respiratory tract, the vasculature, the skin and the ciliary muscle and iris of the eye. The glomeruli of the kidneys contain a smooth muscle like cell called the mesangial cell. Smooth muscle is fundamentally different from skeletal muscle and cardiac muscle in terms of structure and function.

Smooth muscle is a type of non-striated muscle, found within the "walls" of hollow organs and elsewhere like the bladder and abdominal cavity, the uterus, male and female reproductive tracts, the gastrointestinal tract, the respiratory tract, the vasculature, the skin and the ciliary muscle and iris of the eye. The glomeruli of the kidneys contain a smooth muscle like cell called the mesangial cell. Smooth muscle is fundamentally different from skeletal muscle and cardiac muscle in terms of structure and function. Structure

Smooth muscle fibers are spindle shaped, and like all muscle, can contract and relax. In the relaxed state, each cell is spindle-shaped, 20-500 micrometers long and 5 micrometers wide.[1] There are two types of smooth muscle arrangements in the body: multi-unit and single-unit. The single-unit type, also called unitary smooth muscle, is far more common. Whereas the former presents itself as distinct muscle fibers that are usually innervated by their own nerve fibers, the latter operate as a single unit and are arranged in sheets or bundles. Unitary smooth muscle is also commonly referred to as visceral smooth muscle because it it found in the walls of the viscera, or internal organs, of the body, including the intestines, ducts such as the bile ducts, ureters and oviducts, and most blood vessels.[2] Unitary smooth muscle can be further divided into phasic and tonic. The cells that compose smooth muscle generally have single nuclei. The cells are generally arranged in sheets or bundles and connected by gap junctions. In order to contract the cells contain intracellular contractile filamentous proteins called actin and myosin. While the filaments are essentially the same in smooth muscle as they are in skeletal and cardiac muscle, the way they are arranged is different (and some regulatory proteins are different). The smooth muscle cell contains less protein than a typical striated muscle cell and much less myosin. The actin content is similar so the ratio of actin to myosin is ~6:1 in striated muscle and ~15:1 in smooth muscle. Smooth muscle does not contain the proteins troponin or titin, and caldesmon and calponin are significant proteins expressed witin smooth muscle. As non-striated muscle, the actin and myosin is not arranged into distinct sarcomeres that form orderly bands throughout the muscle cell. However there is an organized cytoskeleton consisting of the intermediate filament proteins vimentin and desmin, myosin filaments and actin thin filaments. Actin filaments attach to the sarcolemma by focal adhesions or attachment plaques and attach to other actin filaments via dense bodies (acting much like Z-lines in striated muscle). Evidence indicates that smooth muscle myosin filaments are not bipolar with a central bare zone as in striated muscle, but is either side-polar or row-polar and have no bare zone. Some smooth muscle preparations can be visualized contracting in a spiral corkscrew fashion, and contractile proteins can organize into zones of actin and myosin along the axis of the cell. The sarcolemma possess microdomains specialized to cell signalling events and ion channels called caveolae. These invaginations in the sarcoplasma contain a host of receptors (prostacyclin, endothelin, serotonin, muscarinic receptors, adrenergic receptors), second messenger generators (adenylate cyclase, Phospholipase C), G proteins (RhoA, G alpha), kinases (rho kinase-ROCK, Protein kinase C, Protein Kinase A), ion channels (L type Calcium channels, ATP sensitive Potassium channels, Calcium sensitive Potassium channels) in close proximity. The caveolae are often in close proximity to sarcoplasmic reticulum or mitochondria and have been proposed to organize signaling molecules in the membrane. [edit] Function Muscle follows its function: to maintain organ dimensions against and cells are fastened to one another via adherens junctions. Consequently, cells are mechanically coupled to one another such that contraction of one cell invokes some degree of contraction in an adjoining cell. Gap junctions couple adjacent cells chemically, facilitating the spread of chemicals (e.g., calcium) in single-unit smooth muscle.

Smooth muscle-containing tissue often must be stretched, so elasticity is an important attribute of smooth muscle. Smooth muscle cells may secrete a complex extracellular matrix containing collagen (predominantly types I and III), elastin, glycoproteins, and proteoglycans. These fibers with their extracellular matrices contribute to the viscoelasticity of these tissues. Smooth muscle may contract spontaneously or be induced by a number of physiochemical agents (e.g., hormones, drugs, neurotransmitters). Smooth muscles have been divided into "multi-unit" and "visceral" types or into "phasic" and "tonic" types based on the characteristics of the contractile patterns. It may contract phasically with rapid contraction and relaxation, or tonically with slow and sustained contraction. The reproductive, digestive, respiratory, and urinary tracts, skin, eye, and vasculature all contain this muscle type. For example, contractile function of vascular smooth muscle is critical to regulating the lumenal diameter of the small arteries-arterioles called resistance vessels. The resistance arteries contribute significantly to setting the level of blood pressure. Smooth muscle contracts slowly and may maintain the contraction (tonically) for prolonged periods in blood vessels, bronchioles, and some sphincters. In the digestive tract, smooth muscle contracts in a rhythmic peristaltic fashion. It rhythmically massages products through the digestive tract as the result of phasic contraction. [edit] Contraction and Relaxation Basics Smooth muscle contraction is caused by the sliding of myosin and actin filaments (a sliding filament mechanism) over each other. The energy for this to happen is provided by the hydrolysis of ATP. Myosin functions as an ATPase utilizing ATP to produce a molecular conformational change of part of the myosin and produces movement. Movement of the filaments over each other happens when the globular heads protruding from myosin filaments attach and interact with actin filaments to form crossbridges. The myosin heads tilt and drag along the actin filament a small distance (10-12 nm). The heads then release the actin filament and adopt their original conformation. They can then re-bind to another part of the actin molecule and drag it along further. This process is called crossbridge cycling and is the same for all muscles (see muscle contraction). Unlike cardiac and skeletal muscle, smooth muscle does not contain the calcium binding protein troponin. Contraction is initiated by a calcium regulated phosphorylation of myosin, rather than a calcium activated troponin system. Crossbridge cycling cannot occur until the myosin heads have been activated to allow crossbridges to form. The myosin heads are made up of heavy chains and light protein chains. When the light chains are phosphorylated it becomes active and will allow contraction to occur. The enzyme that phosphorylates the light chains is called myosin light chain kinase (MLCK). In order to control contraction, MLCK will only work when the muscle is stimulated to contract. Stimulation will increase the intracellular concentration of calcium ions. These bind to a molecule called calmodulin and form a calcium-calmodulin complex. It is the complex that will bind to MLCK to activate it, allowing the chain of reactions for contraction to occur. The phosphorylation of the light chains by MLCK is countered by a myosin light chain phosphatase which dephosphorylates the myosin light chains and inhibits the contraction. In general, the relaxation of smooth muscle is by cell signalling pathways that increase the myosin phosphatase activity, decrease the intracellular calcium levels, and/or hyperpolarize the smooth muscle. [edit] Contraction and Relaxation Advanced Muscle can be characterized as two types: tonic and phasic which describes their response to depolarizing high potassium solutions. Tonic smooth muscle contracts and relaxes slowly and exhibits force maintenance such as vascular smooth muscle. Force maintenance is the maintaining of a contraction for a prolonged time with little energy utilization. The phasic smooth muscle contracts and relaxes rapidly such as gut smooth muscle. This phasic response is useful to massage substances through the lumen of the gastrointestinal tract during peristalsis. Vascular smooth muscle (walls of arteries and veins) and visceral smooth muscle (wall of gastrointestinal tract, urogenital tract, iris) is another distinction in common use to discriminate the kind of smooth muscle. Contractions in vertebrate smooth muscle can be initiated by stretch, gap junction electrical, and neural and humoral receptor mediated agents (acetylcholine, endothelin, etc.). Smooth muscle in the gastrointestinal and urogenital tracts is regulated by the enteric nervous system and by peristaltic pacemaker cells -- the interstitial cells of Cajal. Stretch, neural and humoral agents, and gap junction activity that depolarize the sarcolemma increase intracellular calcium. Extracellular calcium enters through L type calcium channels and intracellular calcium is released from stored calcium in the sarcoplasmic reticulum. Calcium release from the sarcoplasmic reticulum is through Ryanodine receptor channels (calcium sparks) by a redox process and inositol triphosphate receptor channels by the second messenger inositol triphosphate. The intracellular calcium binds with calmodulin which then binds and activates myosin-light chain kinase. The calcium-calmodulin-myosin light chain kinase complex phosphorylates the 20 kilodalton (kd) myosin light chains on amino acid residue-serine 19 to initiate contraction. The phosphorylation of the myosin light chains then allows the myosin ATPase to function. The thin filament associated proteins caldesmon and calponin are also believed to serve a function in contractility within smooth muscle. Phosphorylation of the 20 kd myosin light chains correlates well with the shortening velocity of smooth muscle. During this period there is a rapid burst of energy utilization as measured by oxygen consumption. Within a few minutes of initiation the calcium level markedly decrease, 20 kd myosin light chains phosphorylation decreases, and energy utilization decreases and the muscle can relax, however there is a sustained maintenance of force in vascular smooth muscle. The sustained phase has been attributed to slowly cycling dephosphorylated myosin crossbridges and has been termed latch-bridges. During contraction of muscle, rapidly cycling crossbridges form between activated actin and phosphorylated myosin generating force. During the sustained phase, phosphorylation levels decline and slow cycling dephosphorylated crossbridges act as latch bridges to contribute to maintaining the force at low energy costs. Other cell signalling pathways and protein kinases (Protein kinase C, ROCK kinase, Zip kinase, Focal adhesion kinases) have been implcated and actin polymerization dynamics plays a role in force maintenance. While myosin light chain phosphorylation correlates well with shortening velocity, other cell signalling pathways have been implicated in the development of force and maintenance of force. Notably the phosphorylation of specific tyrosine residues on the focal adhesion adapter protein-paxillin by specific tyrosine kinases has been demonstrated to be essential to force development and maintenance. Phosphorylation of the 20kd myosin light chains is counteracted by a myosin light chain phosphatase that dephosphorylates the myosin light chains. Isolated preparations of vascular and visceral smooth muscle contract with depolarizing high potassium balanced saline generating a certain amount of contractile force. The same preparation stimulated in normal balanced saline with an agonist such as endothelin or serotonin will generate more contractile force. This increase in force is termed calcium sensitization. The myosin light chain phosphatase is inhibited to increase the gain or sensitivity of myosin light chain kinase to calcium. There are number of cell signalling pathways believed to regulate this decrease in myosin light chain phosphatase: a RhoA-Rock kinase pathway, a Protein kinase C-Protein kinase C potentiation inhibitor protein 17 (CPI-17) pathway, telokin, and a Zip kinase pathway. Further Rock kinase and Zip kinase have been implicated to directly phosphorylate the 20kd myosin light chains. The relaxation of smooth muscle is mediated by the Endothelium-derived relaxing factor-nitric oxide, endothelial derived hyperpolarizing factor (either an endogenous cannabinoid, cytochrome P450 metabolite, or hydrogen peroxide), or prostacyclin (PGI2). Nitric oxide and PGI2 stimulate soluble guanylate cyclase and membrane bound adenylate cyclase, respectively. These cyclic nucleotides activate Protein Kinase G and Proten Kinase A and phosphorylate a number of proteins. The phosphorylation events lead to a decrease in intracelluar calcium (inhibit L type Calcium channels, inhibits IP3 receptor channels, stimulates sarcoplasmic reticulum Calcium pump ATPase), a decrease in the 20kd myosin light chain phosphorylation by altering calcium sensitization and increasing myosin light chain phosphatase activity, a stimulation of calcium sensitive potassium channels which hyperpolarize the cell, and the phosphorylation of amino acid residue serine 16 on the small heat shock protein (hsp20)by Protein Kinases A and G. The phosphorylation of hsp20 appears to regulate actin and focal adhesion dynamics, and recent evidence indicates that hsp20 binding to 14-3-3 protein is envolved in this process. The endothelium derived hyperpolarizing factor stimulates calcium sensitive potassium channels and/or ATP sensitive potassium channels and stimulate potassium efflux which hyperpolarizes the cell and produces relaxation. [edit] Invertebrate Smooth Muscle In invertebrate smooth muscle, contraction is initiated with calcium directly binding to myosin and then rapidly cycling cross-bridges generating force. Similar to vertebrate smooth muscle there is a low calcium and low energy utilization catch phase. This sustained phase or catch phase has been attributed to a catch protein that has similarities to myosin light chain kinase and the elastic protein-titin called twitchin. Mollusk like clams use this catch phase of smooth muscle to keep their shell closed for prolonged periods with little energy usage. [edit] Control Smooth muscle cells can be stimulated to contract or relax in many different ways. They may be directly stimulated by the autonomic nervous system ("involuntarily" control), but can also react on stimuli from neighbouring cells and on hormones (vasodilators or vasoconstrictor) within the medium that it carries. [edit] Growth and rearrangement The mechanism in which external factors stimulate growth and rearrangement is not yet fully understood. A number of growth factors and neurohumoral agents influence smooth muscle growth and differentiation. The Notch receptor and cell signalling pathway has been demonstrated to be essential to vasculogenesis and the formation of arteries and veins. The embryological origin of smooth muscle is usually of mesodermal origin. However, the smooth muscle within the Aorta and Pulmonary arteries (the Great Arteries of the heart) is derived from ectomesenchyme of neural crest origin, although coronary artery smooth muscle is of mesodermal origin. [edit] Related diseases "Smooth muscle condition" is a condition in which the body of a developing embryo does not create enough smooth muscle for the gastrointestinal system. This condition is fatal.

Anti-smooth muscle antibodies (ASMA) can be a symptom of an auto-immune disorder, such as hepatitis, cirrhosis, or lupus. Vascular smooth muscle tumors are very rare. They can be malignant or benign, and morbidity can be significant with either type. Intravascular leiomyomatosis is a benign neoplasm that extends through the veins, angioleiomyoma is a benign neoplasm of the extremities, vascular leiomyosarcomas is a malign neoplasm that can be found in the inferior vena cava, pulmonary arteries and veins and other peripheral vessels.

See Atherosclerosis.

Sphenoid bone

The sphenoid bone is situated at the base of the skull in front of the temporalis and basilar part of the occipital. It somewhat resembles a bat with its wings extended, and is divided into a median portion or body, two great and two small wings extending outward from the sides of the body, and two Pterygoid processes which project from it below.

Sphenobasilar (SB) junction [48] [49]

The sphenoid articulates with the base of the occipital bone to form the sphenobasilar (SB) junction, one of the most vital articulations in the body. It serves as a “pump” (the sphenobasilar pump) to move cerebrospinal fluid (CSF), which bathes the nervous system, delivering nutrients, removing wastes and modulating the neuroimmune system.

Striated muscle (Skeletal muscle)

Muscle tissue that is marked by transverse dark and light bands, is made up of elongated usually multinucleated fibers, and includes skeletal muscle, cardiac muscle, and most muscle of arthropods. Skeletal muscle is a type of striated muscle, usually attached to the skeleton. Skeletal muscles are used to create movement, by applying force to bones and joints; via contraction. They generally contract voluntarily (via somatic nerve stimulation), although they can contract involuntarily through reflexes. Muscle cells (also called fibers) have an elongated, cylindrical shape, and are multinucleated (in vertebrates and flies). The nuclei of these muscles are located in the peripheral aspect of the cell, just under the plasma membrane, which vacates the central part of the muscle fiber for myofibrils. (Conversely, when the nucleus is located in the center it is considered a pathologic condition known as centronuclear myopathy.) Skeletal muscles have one end (the "origin") attached to a bone closer to the centre of the body's axis and this is often but not always a relatively stationary bone (such as the scapula) and the other end (the "insertion") is attached across a joint to another bone further from the body's axis (such as the humerus). Contraction of the muscle causes the bones to rotate about the joint and the bones to move relative to one another (such as lifting of the upper arm in the case of the origin and insertion described here). There are several different ways to categorize the type of skeletal muscle. One method uses the type of protein contained in myosin (one of the important proteins that is responsible for the ability of muscle to contract). Using this classification scheme, there are two major types of fibers for skeletal muscles: Type I and Type II. Type I fibers appear reddish. They are good for endurance and are slow to tire because they use oxidative metabolism. Type II fibers are whitish; they are used for short bursts of speed and power, and use both oxidative metabolism and anaerobic metabolism depending on the particular sub-type, and are therefore quicker to tire. How skeletal muscle works Main article: Muscle contraction Bodybuilder demonstrating highly developed skeletal muscle. The strength of skeletal muscle is directly proportional to its length and cross-sectional area. The strength of a joint, however, is determined by a number of biomechanical principles, including the distance between muscle insertions and pivot points and muscle size. Muscles are normally arranged in opposition so that as one group of muscles contract, another group 'relaxes' (in fact simply stretched) or lengthens. Antagonism in the transmission of nerve impulses (epsp and ipsp balance) to the muscles means that it is impossible to stimulate the contraction of two antagonistic muscles at any one time. During ballistic motions such as throwing, the antagonist muscles act to 'brake' the agonist muscles throughout the contraction, particularly at the end of the motion. In the example of throwing, the chest and front of the shoulder (anterior Deltoid) contract to pull the arm forward, while the muscles in the back and rear of the shoulder (posterior Deltoid) also contract and undergo eccentric contraction to slow the motion down to avoid injury. Part of the training process is learning to relax the antagonist muscles to increase the force output of the chest and anterior shoulder. Skeletal muscle cells are stimulated by acetylcholine, which is released at neuromuscular junctions by motor neurons.[1] Once the cells are "excited", their sarcoplasmic reticulums will release ionic calcium (Ca2+), this interacts with the myofibrils and induces muscular contraction (via the sliding filament mechanism). Besides calcium, this process requires adenosine triphosphate (ATP). The ATP is produced by metabolizing creatine phosphate and glycogen within the muscle cells by mitochondria, as well by metabolizing glucose and fatty acids, obtained from blood and within the cell. Each motor neuron activates a group of muscle cells, and collectively the neurons and muscle cells are known as motor units. When more strength is required than can be obtained from a single motor unit, more units will be stimulated; this is known as motor unit recruitment. If more strength is required than can be obtained from the current degree of unit contraction, the motor neurons continue to recruit more motor units, and increase the frequency of neuronal firing. This results in tetanic contraction, which causes maximal muscular contraction. [edit] Red and white fibers Skeletal muscles contain two main types of fibers, which differ in the mechanism they use to produce ATP; the amount of each type of fiber varies from muscle to muscle and from person to person. Red ("slow-twitch") fibers have more mitochondria, store oxygen in myoglobin, rely on aerobic metabolism, have a greater capillary to volume ratio and are associated with endurance; these produce ATP more slowly. Marathon runners tend to have more red fibers, generally through a combination of genetics and training. White ("fast-twitch") fibers have fewer mitochondria, are capable of more powerful (but shorter) contractions, metabolize ATP more quickly, have a lower capillary to volume ratio, and are more likely to accumulate lactic acid. Weightlifters and sprinters tend to have more white fibers. Fast fibers come in three varieties, called type IIa, IIx and IIb. Type IIx fibers in people used to be called, confusingly, type IIB. Type IIb fibers predominate in the fast muscle of small mammals that have to accelerate their limbs very fast against little load. Human type IIx (aka IIB) are our fastest fibers. Type IIc fibers are the slowest of all of them, and have only 36 units of myosin.[citation needed] [edit] Characteristics of muscle types

Fiber Type

Type I fibers

Type II a fibers

Type II x fibers

Type II b fibers

Contraction time


Moderately Fast


Very fast

Size of motor neuron




Very large

Resistance to fatigue


Fairly high



Activity Used for


Long-term anaerobic

Short-term anaerobic

Short-term anaerobic

Maximum duration of use


<30 minutes

<5 minutes

<1 minute

Force production




Very high

Mitochondrial density





Capillary density





Oxidative capacity





Glycolytic capacity





Major storage fuel


Creatine phosphate, glycogen

Creatine phosphate, glycogen

Creatine phosphate, glycogen

[edit] Genes that define skeletal muscle phenotype Skeletal muscle fiber-type phenotype in adult animals, and probably people, is regulated by several independent signaling pathways. These include pathways involved with the Ras/mitogen-activated protein kinase (MAPK), calcineurin, calcium/calmodulin-dependent protein kinase IV, and the peroxisome proliferator γ coactivator 1 (PGC-1). The Ras/MAPK signaling pathway links the motor neurons and signaling systems, coupling excitation and transcription regulation to promote the nerve-dependent induction of the slow program in regenerating muscle. Calcineurin, a Ca2+/calmodulin-activated phosphatase implicated in nerve activity-dependent fiber-type specification in skeletal muscle, directly controls the phosphorylation state of the transcription factor NFAT, allowing for its translocation to the nucleus and leading to the activation of slow-type muscle proteins in cooperation with myocyte enhancer factor 2 (MEF2) proteins and other regulatory proteins. Calcium-dependent Ca2+/calmodulin kinase activity is also upregulated by slow motor neuron activity, possibly because it amplifies the slow-type calcineurin-generated responses by promoting MEF2 transactivator functions and enhancing oxidative capacity through stimulation of mitochondrial biogenesis.

Contraction-induced changes in intracellular calcium or reactive oxygen species provide signals to diverse pathways that include the MAPKs, calcineurin and calcium/calmodulin-dependent protein kinase IV to activate transcription factors that regulate gene expression and enzyme activity in skeletal muscle.

Exercise-Included Signaling Pathways in Skeletal Muscle That Determine Specialized Characteristics of ST and FT Muscle Fibers

Exercise-Included Signaling Pathways in Skeletal Muscle That Determine Specialized Characteristics of ST and FT Muscle Fibers PGC1-α, a transcriptional coactivator of nuclear receptors important to the regulation of a number of mitochondrial genes involved in oxidative metabolism, directly interacts with MEF2 to synergistically activate selective ST muscle genes and also serves as a target for calcineurin signaling. A peroxisome proliferator-activated receptor δ (PPARδ)-mediated transcriptional pathway is involved in the regulation of the skeletal musclefiber phenotype. Mice that harbor an activated form of PPARd display an “endurance” phenotype, with a coordinated increase in oxidative enzymes and mitochondrial biogenesis and an increased proportion of ST fibers. Thus—through functional genomics—calcineurin, calmodulin-dependent kinase, PGC-1α, and activated PPARδ form the basis of a signaling network that controls skeletal muscle fiber-type transformation and metabolic profiles that protect against insulin resistance and obesity. The transition from aerobic to anaerobic metabolism during intense work requires that several systems are rapidly activated to ensure a constant supply of ATP for the working muscles. These include a switch from fat-based to carbohydrate-based fuels, a redistribution of blood flow from nonworking to exercising muscles, and the removal of several of the byproducts of anaerobic metabolism, such as carbon dioxide and lactic acid. Some of these responses are governed by transcriptional control of the FT glycolytic phenotype. For example, skeletal muscle reprogramming from a ST glycolytic phenotype to a FT glycolytic phenotype involves the Six1/Eya1 complex, composed of members of the Six protein family. Moreover, the Hypoxia Inducible Factor-1α (HIF-1α) has been identified as a master regulator for the expression of genes involved in essential hypoxic responses that maintain ATP levels in cells. Ablation of HIF-1α in skeletal muscle was associated with an increase in the activity of bob-limiting enzymes of the mitochondria, indicating that the citric acid cycle and increased fatty acid oxidation may be compensating for decreased flow through the glycolytic pathway in these animals. However, hypoxia-mediated HIF-1α responses are also linked to the regulation of mitochondrial dysfunction through the formation of excessive reactive oxygen species in mitochondria. Other pathways also influence adult muscle character. For example, physical force inside a muscle fiber may release the transcription factor Serum Response Factor (SRF) from the structural protein titin, leading to altered muscle growth.

Sympathetic ganglion

Sympathetic ganglia are the ganglia of the sympathetic nervous system. They deliver information to the body about stress and impending danger, and are responsible for the familiar fight-or-flight response. They contain approximately 20000–30000 nerve cell bodies and are located close to and either side of the spinal cord in long chains. The bilaterally symmetric sympathetic chain ganglia, also called the paravertebral ganglia, are located just anterior and lateral to the spinal cord. The chain extends from the upper neck down to the coccyx, forming the unpaired coccygeal ganglion. Preganglionic nerves from the spinal cord synapse at one of the chain ganglia and the postganglionic fiber extends to an effector, typically a visceral organ in the thoracic cavity. Neurons of the collateral ganglia, also called the prevertebral ganglia, receive input from the splanchnic nerves and innervate organs of the abdominal and pelvic region. These include the celiac ganglia, superior mesenteric ganglia, and inferior mesenteric ganglia.

Sympathetic nervous system

The Sympathetic Nervous System (SNS) is a branch of the autonomic nervous system. It is always active at a basal level (called sympathetic tone) and becomes more active during times of stress. Its actions during the stress response comprise the fight-or-flight response. Like other parts of the nervous system, the sympathetic nervous system operates through a series of interconnected neurons. Sympathetic neurons are frequently considered part of the peripheral nervous system (PNS), although there are many that lie within the central nervous system (CNS). Sympathetic neurons of the spinal cord (which is part of the CNS) communicate with peripheral sympathetic neurons via a series of sympathetic ganglia. Within the ganglia, spinal cord sympathetic neurons join peripheral sympathetic neurons through chemical synapses. Spinal cord sympathetic neurons are therefore called presynaptic (or preganglionic) neurons, while peripheral sympathetic neurons are called postsynaptic (or postganglionic) neurons. At synapses within the sympathetic ganglia, preganglionic sympathetic neurons release acetylcholine, a chemical messenger that binds and activates nicotinic acetylcholine receptors on postganglionic neurons. In response to this stimulus, postganglionic neurons principally release noradrenaline (norepinephrine). Prolonged activation can elicit the release of adrenaline from the adrenal medulla. Once released, noradrenaline and adrenaline bind adrenergic receptors on peripheral tissues. Binding to adrenergic receptors causes the effects seen during the fight-or-flight response. These include pupil dilation, increased sweating, increased heart rate, and increased blood pressure.


Detect changes in temperature

Thoracic splanchnic nerves

Thoracic splanchnic nerves arise from the sympathetic trunk in the thorax and travel inferiorly to provide sympathetic innervation to the abdomen. The nerves contain preganglionic sympathetic and visceral afferent fibers. There are three main thoracic splanchnic nerves: greater[1]= T5-T9[2] or T5-T10[3]= The nerve travels through the diaphragm and enters the abdominal cavity, where its fibers synapse at the celiac ganglia. The nerve contributes to the celiac plexus, a network of nerves located in the vicinity of where the celiac trunk branches from the abdominal aorta. The fibers in this nerve modulate the activity of the enteric nervous system of the foregut. They also provide the sympathetic innervation to the adrenal medulla, stimulating catecholamine release. lesser[4]= T9-T12, T9-T10[4][5], T10-T12, or T10-T11[3]= The nerve travels inferiorly, lateral to the greater splanchnic nerve. Its fibers synapse with their postganglionic counterparts in the celiac ganglia, or in the aorticorenal ganglion. The nerve modulates the activity of the enteric nervous system of the midgut. least or lowest[6]= T12-L2, or T11-T12[7]= The nerve travels into the abdomen, where its fibers synapse in the renal ganglia.

Tom Gordon (1918-2002)

World-renowned psychologist, Dr. Thomas Gordon, author of Parent Effectiveness Training (P.E.T.) and founder of Gordon Training International of Solana Beach, California, died Monday, August 26, after a bout with prostate cancer. He was 84. Dr. Gordon spent more than 50 years teaching parents, teachers and leaders the model he developed for building effective relationships. His model was based on a strong belief that the use of coercive power damages relationships. As an alternative, he taught people skills for communicating and resolving conflicts that they can use to build and maintain good relationships at home, school and at work. These skills, which include Active Listening, I-Messages and No-Lose Conflict Resolution, are now widely known and used by people around the world. Dr. Gordon first applied some of these methods in the 1950s as a consultant to business organizations. Then, in the early 60s, he developed the Parent Effectiveness Training course—commonly known as P.E.T.—and taught the first class to a group of 14 parents in a Pasadena, CA cafeteria. The courses proved to be so popular with parents that he began training instructors throughout the U.S. to teach it in their communities. Over the next several years, the course spread to all 50 states.

Unconditional positive regard

Unconditional positive regard (UPR) is a concept in client-centered therapy. Carl Rogers, who created client-centered therapy, designated unconditional positive regard as one of the three conditions were necessary for positive change, along with empathy and genuineness (congruence). Unconditional positive regard encourages the therapist, termed a counselor by Rogers, to treat the client as worthy and capable, even when the client does not act or feel that way. According to the Rogers's theory, mental illness is often caused by the absence of love, or by a defective kind of love, that the client received as a child. By showing the client unconditional positive regard and acceptance, the therapist is providing the best possible conditions for personal growth to the client. To practice unconditional positive regard, while maintaining congruence at all times, the therapist provides specific feedback. The counselors show and demonstrate their care with their actions. If a clinician finds it hard to unconditionally regard their patient in a positive light, they need to keep in mind Rogers’ belief that all people have the internal resources required for personal growth. According to this theory, it is the environment that can make the difference as to whether growth occurs. A patient’s past environment may have been such that patterns of behaviour were developed in order to survive in that environment. These patterns can become entrenched so that the patient continues to operate in the world with them even if they are no longer appropriate. It is usually an inappropriate pattern that makes it hard for the clinician to regard their clients positively. The clinician needs to feel for the person under those patterns and for the person who was damaged and then survived by adapting by developing the patterns that are no longer appropriate. Unconditional positive regard has been described as the opposite of unconditional negative disgust, a term coined by therapist- Matt Vaughn

Vagus nerve

The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the neck, chest and abdomen.

The medieval Latin word vagus means literally "Wandering" (the words vagrant, vagabond, and vague come from the same root). It is also called the pneumogastric nerve since it innervates both the lungs and the stomach. The vagus nerve supplies motor parasympathetic fibers to all the organs except the suprarenal (adrenal) glands, from the neck down to the second segment of the transverse colon. The vagus also controls a few skeletal muscles


In anatomy, a viscus (plural: viscera) is an internal organ of an animal (including humans), in particular an internal organ of the thorax or abdomen. The viscera, when removed from a butchered animal, are known collectively as offal. Internal organs are also known as "innards", or less formally, "guts" (which may also refer to the gastrointestinal tract). The adjective visceral is used for anything pertaining to the internal organs. Historically, viscera of animals were examined by Roman pagan priests like the haruspices or the augurs in order to divine the future by their shape, dimensions or other factors.

Visceroceptors (Enteroceptors)

Provide information about the internal environment. These sensations arise from within the body and may be felt as pain, pressure, fatique, hunger, thirst and nausea. Visceroceptors are located in blood vessels and viscera.


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