Physiology Health Dictionary

The structure of the body of any living thing, and its scientific study. Human anatomy, together with physiology (the study of the functioning of the body), forms the foundation of medical science. Anatomy is subdivided into many branches. These include comparative anatomy (the study of the differences between human and animal bodies), surgical anatomy (the practical knowledge required by surgeons), embryology (the study of structural changes that occur during the development of the embryo and fetus), systematic anatomy (the study of the structure of particular body systems), and cytology and histology (the microscopic study of cells and tissues respectively).... anatomy

Also known as suprarenal glands, these are two small triangular ENDOCRINE GLANDS situated one upon the upper end of each kidney. (See diagram of ABDOMEN.)

Structure Each suprarenal gland has an enveloping layer of ?brous tissue. Within this, the gland shows two distinct parts: an outer, ?rm, deep-yellow cortical (see CORTEX) layer, and a central, soft, dark-brown medullary (see MEDULLA) portion. The cortical part consists of columns of cells running from the surface inwards, whilst in the medullary portion the cells are arranged irregularly and separated from one another by large capillary blood vessels.

Functions Removal of the suprarenal glands in animals is speedily followed by great muscular prostration and death within a few days. In human beings, disease of the suprarenal glands usually causes ADDISON’S DISEASE, in which the chief symptoms are increasing weakness and bronzing of the skin. The medulla of the glands produces a substance – ADRENALINE – the effects of which closely resemble those brought about by activity of the SYMPATHETIC NERVOUS SYSTEM: dilated pupils, hair standing on end, quickening and strengthening of the heartbeat, immobilisation of the gut, increased output of sugar from the liver into the bloodstream. Several hormones (called CORTICOSTEROIDS) are produced in the cortex of the gland and play a vital role in the metabolism of the body. Some (such as aldosterone) control the electrolyte balance of the body and help to maintain the blood pressure and blood volume. Others are concerned in carbohydrate metabolism, whilst others again are concerned with sex physiology. HYDROCORTISONE is the most important hormone of the adrenal cortex, controlling as it does the body’s use of carbohydrates, fats and proteins. It also helps to suppress in?ammatory reactions and has an in?uence on the immune system.... adrenal glands

Chiropody (also termed podiatry) is that part of medical science which is concerned with the health of the feet. Its practitioners are specialists capable of providing a fully comprehensive foot-health service. This includes the palliation of established deformities and dysfunction, both as short-term treatment for immediate relief of painful symptoms and as long-term management to secure optimum results. This requires the backing of e?ective appliances and footwear services. It also involves curative foot-care, including the use of various therapeutic techniques, including minor surgery and the prescription and provision of specialised and individual appliances.

Among conditions routinely treated are walking disorders in children, injuries to the feet of joggers and athletes, corns, bunions and hammer toes, ulcers and foot infections. Chiropody also has a preventative role which includes inspection of children’s feet and the detection of foot conditions requiring treatment and advice and also foot-health education. The chiropodist is trained to recognise medical conditions which manifest themselves in the feet, such as circulatory disorders, DIABETES MELLITUS and diseases causing ulceration.

The only course of training in the United Kingdom recognised for the purpose of state registration by the Health Professionals Council is the Society of Chiropodists’ three-year full-time course. The course includes instruction and examination in the relevant aspects of anatomy and physiology, local analgesia, medicine and surgery, as well as in podology and therapeutics. The Council holds the register of podiatrists. (See APPENDIX 2: ADDRESSES: SOURCES OF INFORMATION, ADVICE, SUPPORT AND SELFHELP.)... chiropody

Individual outcome measure that extends beyond traditional measures of mortality and morbidity to include such dimensions as physiology, function, social activity, cognition, emotion, sleep and rest, energy and vitality, health perception and general life satisfaction (some of these are also known as health status, functional status or quality-of-life measures).... health-related quality-of-life (hrql) measure

Professionally trained speech therapists assist, diagnose and treat the whole spectrum of acquired or developmental communication disorders. They work in medical and education establishments, often in an advisory or consultative capacity. The medical conditions in which speech therapy is employed include: dysgraphia, DYSLEXIA, DYSARTHRIA, DYSPHASIA, DYSPHONIA, DYSPRAXIA, AUTISM, BELL’S PALSY, CEREBRAL PALSY, DEAFNESS, disordered language, delayed speech, disordered speech, DOWN’S (DOWN) SYNDROME, LARYNGECTOMY, LEARNING DISABILITY, MACROGLOSSIA, MOTOR NEURONE DISEASE (MND), malformations of the PALATE, PARKINSONISM, STAMMERING, STROKE and disorders of voice production.

Speech therapists form a small independent profession, most of whom work for the National Health Service in community clinics, general practices and hospitals. They may also work in schools or in units for the handicapped, paediatric assessment centres, language units attached to primary schools, adult training centres and day centres for the elderly.

A speech therapist undergoes a four-year degree course which covers the study of disorders of communication in children and adults, phonetics and linguistics, anatomy and physiology, psychology and many other related subjects. Further information on training can be obtained from the College of Speech Therapists.

If the parents of a child are concerned about their child’s speech, they may approach a speech therapist for assessment and guidance. Their general practitioner will be able to give them local addresses or they should contact the district speech therapist. Adults are usually referred by hospital consultants.

The College of Speech Therapists keeps a register of all those who have passed a recognised degree or equivalent quali?cation in speech therapy. It will be able to direct you to your nearest NHS or private speech therapist.... speech therapy

Chemical substances manufactured by the endocrine glands and secreted directly into the bloodstream. As the heart pumps blood through the body they are borne to cells remote from their point of origin where they have a specific effect. Hormones are to physiology what radium is to chemistry. ... hormones

Muscular tissue is divided, according to its function, into three main groups: voluntary muscle, involuntary muscle, and skeletal muscle – of which the ?rst is under control of the will, whilst the latter two discharge their functions independently. The term ‘striped muscle’ is often given to voluntary muscle, because under the microscope all the voluntary muscles show a striped appearance, whilst involuntary muscle is, in the main, unstriped or plain. Heart muscle is partially striped, while certain muscles of the throat, and two small muscles inside the ear, not controllable by willpower, are also striped.

Structure of muscle Skeletal or voluntary muscle forms the bulk of the body’s musculature and contains more than 600 such muscles. They are classi?ed according to their methods of action. A ?exor muscle closes a joint, an extensor opens it; an abductor moves a body part outwards, an adductor moves it in; a depressor lowers a body part and an elevator raises it; while a constrictor (sphincter) muscle surrounds an ori?ce, closing and opening it. Each muscle is enclosed in a sheath of ?brous tissue, known as fascia or epimysium, and, from this, partitions of ?brous tissue, known as perimysium, run into the substance of the muscle, dividing it up into small bundles. Each of these bundles consists in turn of a collection of ?bres, which form the units of the muscle. Each ?bre is about 50 micrometres in thickness and ranges in length from a few millimetres to 300 millimetres. If the ?bre is cut across and examined under a high-powered microscope, it is seen to be further divided into ?brils. Each ?bre is enclosed in an elastic sheath of its own, which allows it to lengthen and shorten, and is known as the sarcolemma. Within the sarcolemma lie numerous nuclei belonging to the muscle ?bre, which was originally developed from a simple cell. To the sarcolemma, at either end, is attached a minute bundle of connective-tissue ?bres which unites the muscle ?bre to its neighbours, or to one of the connective-tissue partitions in the muscle, and by means of these connections the ?bre affects muscle contraction. Between the muscle ?bres, and enveloped in a sheath of connective tissue, lie here and there special structures known as muscle-spindles. Each of these contains thin muscle ?bres, numerous nuclei, and the endings of sensory nerves. (See TOUCH.) The heart muscle comprises short ?bres which communicate with their neighbours via short branches and have no sarcolemma.

Plain or unstriped muscle is found in the following positions: the inner and middle coats of the STOMACH and INTESTINE; the ureters (see URETER) and URINARY BLADDER; the TRACHEA and bronchial tubes; the ducts of glands; the GALL-BLADDER; the UTERUS and FALLOPIAN TUBES; the middle coat of the blood and lymph vessels; the iris and ciliary muscle of the EYE; the dartos muscle of the SCROTUM; and in association with the various glands and hairs in the SKIN. The ?bres are very much smaller than those of striped muscle, although they vary greatly in size. Each has one or more oval nuclei and a delicate sheath of sarcolemma enveloping it. The ?bres are grouped in bundles, much as are the striped ?bres, but they adhere to one another by cement material, not by the tendon bundles found in voluntary muscle.

Development of muscle All the muscles of the developing individual arise from the central layer (mesoderm) of the EMBRYO, each ?bre taking origin from a single cell. Later on in life, muscles have the power both of increasing in size – as the result of use, for example, in athletes – and also of healing, after parts of them have been destroyed by injury. An example of the great extent to which unstriped muscle can develop to meet the demands made on it is the uterus, whose muscular wall develops so much during pregnancy that the organ increases from the weight of 30–40 g (1–1••• oz.) to a weight of around 1 kg (2 lb.), decreasing again to its former small size in the course of a month after childbirth.

Physiology of contraction A muscle is an elaborate chemico-physical system for producing heat and mechanical work. The total energy liberated by a contracting muscle can be exactly measured. From 25–30 per cent of the total energy expended is used in mechanical work. The heat of contracting muscle makes an important contribution to the maintenance of the heat of the body. (See also MYOGLOBIN.)

The energy of muscular contraction is derived from a complicated series of chemical reactions. Complex substances are broken down and built up again, supplying each other with energy for this purpose. The ?rst reaction is the breakdown of adenyl-pyrophosphate into phosphoric acid and adenylic acid (derived from nucleic acid); this supplies the immediate energy for contraction. Next phosphocreatine breaks down into creatine and phosphoric acid, giving energy for the resynthesis of adenyl-pyrophosphate. Creatine is a normal nitrogenous constituent of muscle. Then glycogen through the intermediary stage of sugar bound to phosphate breaks down into lactic acid to supply energy for the resynthesis of phosphocreatine. Finally part of the lactic acid is oxidised to supply energy for building up the rest of the lactic acid into glycogen again. If there is not enough oxygen, lactic acid accumulates and fatigue results.

All of the chemical changes are mediated by the action of several enzymes (see ENZYME).

Involuntary muscle has several peculiarities of contraction. In the heart, rhythmicality is an important feature – one beat appearing to be, in a sense, the cause of the next beat. Tonus is a character of all muscle, but particularly of unstriped muscle in some localities, as in the walls of arteries.

Fatigue occurs when a muscle is made to act for some time and is due to the accumulation of waste products, especially sarcolactic acid (see LACTIC ACID). These substances affect the end-plates of the nerve controlling the muscle, and so prevent destructive overaction of the muscle. As they are rapidly swept away by the blood, the muscle, after a rest (and particularly if the rest is accompanied by massage or by gentle contractions to quicken the circulation) recovers rapidly from the fatigue. Muscular activity over the whole body causes prolonged fatigue which is remedied by rest to allow for metabolic balance to be re-established.... muscle

A term used in several di?erent senses. Generally speaking, it is applied to anything which agrees with the regular and established type. In chemistry, the term is applied to solutions of acids or bases of such strength that each litre contains the number of grams corresponding to the molecular weight of the substance in question. In physiology the term ‘normal’ is applied to solutions of such strength that, when mixed with a body ?uid, they are ISOTONIC and cause no disturbance: for example, normal saline solution.... normal

n. (in physiology) the uptake of fluids or other substances by the tissues of the body. Digested food is absorbed into the blood and lymph from the alimentary canal. Most absorption of food occurs in the small intestine – in the jejunum and ileum – although alcohol is readily absorbed from the stomach. The small intestine is lined with minute finger-like processes (see villus), which greatly increase its surface area and therefore the speed at which absorption can take place. See also assimilation; digestion.... absorption

The ?eld of medicine concerned with physical ?tness and the diagnosis and treatment of both acute and chronic sports injuries sustained during training and competition. Acute injuries are extremely common in contact sports, and their initial treatment is similar to that of those sustained in other ways, such as falls and road traf?c incidents. Tears of the muscles (see MUSCLES, DISORDERS OF), CONNECTIVE TISSUE and LIGAMENTS which are partial (sprains) are initially treated with rest, ice, compression, and elevation (RICE) of the affected part. Complete tears (rupture) of ligaments (see diagrams) or muscles, or fractures (see BONE, DISORDERS OF – Bone fractures) require more prolonged immobilisation, often in plaster, or surgical intervention may be considered. The rehabilitation of injured athletes requires special expertise

– an early graded return to activity gives the best long-term results, but doing too much too soon runs the risk of exacerbating the original injury.

Chronic (overuse) injuries affecting the bones (see BONE), tendons (see TENDON) or BURSAE of the JOINTS are common in many sports. Examples include chronic INFLAMMATION of the common extensor tendon where it

attaches to the later EPICONDYLE of the humerus – common in throwers and racquet sportspeople – and stress fractures of the TIBIA or METATARSAL BONES of the foot in runners. After an initial period of rest, management often involves coaching that enables the athlete to perform the repetitive movement in a less injury-susceptible manner.

Exercise physiology is the science of measuring athletic performance and physical ?tness for exercise. This knowledge is applied to devising and supervising training regimens based on scienti?c principles. Physical ?tness depends upon the rate at which the body can deliver oxygen to the muscles, known as the VO2max, which is technically di?cult to measure. The PULSE rate during and after a bout of exercise serves as a good proxy of this measurement.

Regulation of sport Sports medicine’s role is to minimise hazards for participants by, for example, framing rule-changes which forbid collapsing the scrum, which has reduced the risk of neck injury in rugby; and in the detection of the use of drugs taken to enhance athletic performance. Such attempts to gain an edge in competition undermine the sporting ideal and are banned by leading sports regulatory bodies. The Olympic Movement Anti-Doping Code lists prohibited substances and methods that could be used to enhance performance. These include some prohibited in certain circumstances as well as those completely banned. The latter include:

stimulants such as AMPHETAMINES, bromantan, ca?eine, carphedon, COCAINE, EPHEDRINE and certain beta-2 agonists.

NARCOTICS such as DIAMORPHINE (heroin), MORPHINE, METHADONE HYDROCHLORIDE and PETHIDINE HYDROCHLORIDE.

ANABOLIC STEROIDS such as methandione, NANDROLONE, stanazol, TESTOSTERONE, clenbuterol, androstenedone and certain beta-2 agonists.

peptide HORMONES, mimetics and analogues such as GROWTH HORMONE, CORTICOTROPHIN, CHORIONIC GONADOTROPHIC HORMONE, pituitary and synthetic GONADOTROPHINS, ERYTHROPOIETIN and INSULIN. (The list produced above is not comprehen

sive: full details are available from the governing bodies of relevant sports.) Among banned methods are blood doping (pre-competition administration of an athlete’s own previously provided and stored blood), administration of arti?cial oxygen carriers or plasma expanders. Also forbidden is any pharmacological, chemical or physical manipulation to affect the results of authorised testing.

Drug use can be detected by analysis of the URINE, but testing only at the time of competition is unlikely to detect drug use designed to enhance early-season training; hence random testing of competitive athletes is also used.

The increasing professionalism and competitiveness (among amateurs and juveniles as well as professionals) in sports sometimes results in pressures on participants to get ?t quickly after injury or illness. This can lead to

players returning to their activity before they are properly ?t – sometimes by using physical or pharmaceutical aids. This practice can adversely affect their long-term physical capabilities and perhaps their general health.... sports medicine

This is carried out by closing the mouth, holding the nose and attempting to blow hard. The manoeuvre raises pressure in the chest – and, indirectly, the abdomen – and forces air from the back of the nose down the EUSTACHIAN TUBES to the middle ear. This latter e?ect can be used to clear the tube during descent in an aircraft, when it sometimes becomes blocked or partially blocked, producing di?erential pressures on the two sides of each eardrum, usually accompanied by temporary pain and deafness.

Valsalva’s manoeuvre is involuntarily performed when a person strains to open his or her bowels: in these circumstances the passage of air to the lungs is blocked by instinctive closure of the vocal cords in the LARYNX. The resultant raised abdominal pressure helps to expel the bowel contents. The manoeuvre is also used in the study of cardiovascular physiology because the rise in pressure in the chest restricts the return of venous blood to the right atrium of the HEART. Pressure in the peripheral VEINS is raised and the amount of blood entering and leaving the heart falls. This drop in cardiac output may cause the subject to faint because the supply of oxygenated blood to the brain is reduced.... valsalva’s manoeuvre

n. (in physiology) the entire process of excretion of metabolic waste products from the blood by the kidneys and urinary tract.... elimination

n. (in physiology) the coupling of the output of a process to the input. Feedback mechanisms are important in regulating many physiological processes; for example, the production of hormones and neurotransmitters. In negative feedback, a rise in the output of a substance will inhibit a further increase in its production, either directly or indirectly (see negative feedback loop). In positive feedback, a rise in the output of a substance is associated with an increase in the output of another substance, either directly or indirectly.... feedback

n. (in physiology) sluggishness or absence of activity in certain smooth muscles. In uterine inertia the muscular wall of the uterus fails to contract adequately during labour, making the process excessively long. This inertia may be present from the start of labour or it may develop because of exhaustion following strong contractions and can lead to increased risk of atonic *postpartum haemorrhage. See also shoulder dystocia.... inertia

Gradual loss of sight following chemical disturbance in the lens protein of the eye resulting in degeneration and loss of transparency. Greyish white pupil which in normality is jet black. Occurs chiefly in the elderly due to injury of the lens capsule, glaucoma, the use of microwave or diet-mineral deficiency (calcium). In the ageing process there is a lack of antioxidant protection of the lens usually due to low Vitamin C, the major antioxidant in lens physiology. May also be congenital.

High blood glucose levels, diabetes, drugs, steroids, Down’s syndrome, kidney failure, uraemia and chronic diarrhoea predispose. There is no pain. Vision is as if looking through a frosted glass.

Treatment. Restore lens metabolism.

“My father-in-law knew people who had been cured by steeping Wild Burdock burrs and taking a small drink 3-4 times a day” (John Tobe, in “Cataract, Glaucoma and other Eye Disorders”) Cider Vinegar. 2 teaspoons to glass water, sips once or twice daily.

Chinese medicine. Hachimi jiogan to increase glutathione content of the lens.

Topical. Greater Celandine. 5-10 drops fresh juice of plant to 4oz distilled extract Witch Hazel. 10-20 drops in an eyebath half filled with warm water; use as a douche.

Cineraria maritima (Dusty Miller). 2-3 drops fresh plant juice applied to the eye with a medicine dropper. Same refers to Yucca and Chaparral. For early non-diabetic cataract.

Diet. Lacto-vegetarian. Carrot juice. Brewer’s Yeast, yellow-green vegetables. Spinach as an item of diet appears to reduce risk of cataract.

Supplementation. Vitamin C slows down the ageing process of the lens, protecting it from damage by free radicals: 1500mg daily. Vitamin B2. Vitamin E, 400iu daily. Selenium, 200mcg daily. Amino acids: cysteine, methionine, glutathione.

General. Surgical treatment is invariably successful. Cold packs and manipulation of the neck improve circulation and drainage of the head. ... cataract

Expressionless eye with pinpoint pupil (pupil constriction). The iris is compressed against the cornea thus arresting fluid circulation and raising intra-ocular pressure. Medical emergency. Two kinds: acute (closed angle) and chronic.

Acute. Eye is brick red and brick hard. Agonisingly painful, vision much reduced, pupil dilated and oval, the cornea steamy and the iris greenish, sees rainbow rings around lights, misty vision, pain in head and eyes, colours appear dull, can read for only short periods, unable to walk confidently downstairs, damage to retina and optic nerve from build-up of fluid.

Etiology: Damage from past inflammations, high blood pressure, steroids, stress, diet deficiencies, injury. Develops more in far-sighted people.

Ocular emergency requiring immediate hospital specialist treatment. If admission to hospital is delayed Pilocarpine may save the day: 1 drop of 1 per cent solution to each eye to constrict the pupil and open the drainage angle. This lasts 4-5 hours. Apply 1 drop 4 times every 24 hours. In the absence of Pilocarpine, a practitioner may prescribe Tincture Gelsemium BPC 1963, 5 drops in water not more than thrice daily.

A history of eyelids that are stuck down in the mornings reveals blockage from inflammatory exudate, tension rises and may precipitate glaucoma.

Chronic (gradual and long-continued). Usually in the elderly. Sometimes genetic. Chronic rise in painless intra-ocular pressure arrests blood supply to the optic discs thus disrupting bundles of retinal nerve fibres. ‘Deeply cupped discs’. Condition usually unsuspected. A sight destroyer.

Symptoms: bumping into objects and people. As above.

Treatment. Surgical drainage incision through the iris relieves tension. The object is to contract the pupil and focussing (ciliary) muscle which promotes the escape of watery fluid from the eye. Agents which contract the pupil are Pilocarpine, Adrenalin. Promotion of the body’s own supply of Adrenalin is mildly assisted by Ginseng. All cases should receive Echinacea to enhance resistance. Herbal medicine often stabilises the condition, with remedies such as Pulsatilla.

Alternatives:– Maintenance anti-inflammatory. Tea: fresh or dried herbs. Equal parts: Nettles, Marigold petals, Horsetail. Mix. 2 teaspoons to each cup boiling water; infuse 15 minutes. Dose: half-1 cup thrice daily.

Traditional. It was common practice in the South of France to douche the eye with dilute lemon juice, doubtless because Vitamin C has an osmotic effect, drawing away fluid.

Rutin (Buckwheat). 20mg thrice daily. Tablets, powder, etc.

Canasol. A non-hallucinogenic alkaloid of the marijuana plant (cannabis) has been used with success. Blood Tonics. See entry. Healthy blood contributes to healthy eyes and common blood tonics have been responsible for some cures in the early stages.

Bilberries. Mr Eric Wright suffered from glaucoma for many years. At 74 he was nearly blind, walked with a white stick, and couldn’t read or write. Improvement was impressive after taking Bilberry extract. His specialist agreed that his sight was at its best in three years since surgery to reduce intra-ocular pressure.

Diet. Begin 3-day fast, followed by 3 days on fruit and vegetable juices. Wholefoods thereafter. Increase protein intake. Repeat fast every 3 months. Fresh Bilberries as desired. Dr Rolf Ulrich links coffee with glaucoma. (Clinical Physiology)

Supplements. Daily. Vitamin A 7500iu, Vitamin B1 15mg, Vitamin B2 10mg, Vitamin B6 10mg, Vitamin C 3g, Vitamin E 500mg, Zinc.

Notes. Stress automatically raises intra-ocular pressure for which relaxation techniques are indicated. Tobacco worsens by causing constriction of blood vessels supplying the optic nerve. Abstain alcohol. Glaucoma becomes more prevalent in an ageing population. Patients with a strong history and with high blood pressure and diabetes should be screened.

To be treated by a general medical practitioner or hospital specialist. ... glaucoma

n. 1. (in physiology) the prevention or reduction of the functioning of an organ, muscle, etc., by the action of certain nerve impulses. 2. (in psychoanalysis) an inner command that prevents one from doing something forbidden. Some inhibitions are essential for social adjustment, but excessive inhibitions can severely restrict one’s life.... inhibition

n. 1. (in physiology) the property of certain kinds of tissue that enables them to respond in a specific way to outside stimuli. Irritability is shown by nerve cells, which can generate and transmit electrical impulses when stimulated appropriately, and by muscle cells, which contract when stimulated by nerve impulses. 2. impatience and lack of *empathy. This has been found to be a major factor in patients’ dissatisfaction with their medical advisors.... irritability

The use of animals in research to provide information about animal biology or, by inference, human physiology or behaviour. Animal research has contributed to the development of drugs, such as vaccines, and surgical techniques, such as transplant surgery. However, because of ethical concerns, alternative practices, such as cell cultures, are now used wherever possible.

animals, diseases from See zoonosis. anisometropia Unequal focusing power in the 2 eyes, usually due to a difference in size and/or shape of the eyes, that causes visual discomfort. For example, one eye may be normal and the other affected by myopia (shortsightedness), hypermetropia (longsightedness), or astigmatism (uneven curvature of the cornea). Glasses or contact lenses correct the problem in most cases. ankle joint The hinge joint between the foot and the leg. The talus (uppermost bone in the foot) fits between the 2 bony protuberances formed by the lower ends of the tibia (the shinbone) and the fibula (the outer bone of the lower leg). Strong ligaments on either side of the ankle joint give it support. The ankle allows for up-anddown movement of the foot.

An ankle sprain is one of the most

common injuries.

It is usually caused by twisting the foot over on to its outside edge, causing overstretching and bruising of the ligaments.

Violent twisting of the ankle can cause a combined fracture and dislocation known as Pott’s fracture.... animal experimentation

adj. (in physiology) relating to the threshold of perception.... liminal

(physio-) combining form denoting 1. physiology. 2. physical.... physi

n. 1. (in physiology) the phenomenon whereby an increase in the strength of a stimulus or repetition of the stimulus will stimulate increasing numbers of nerve cells to respond. 2. (in audiology) the phenomenon in which a person with sensorineural deafness cannot hear quiet sounds but can perceive loud sounds just as loudly as, or even more loudly than, a person with normal hearing.... recruitment

n. (in physiology) the diminution of tension in a muscle, which occurs when it ceases to contract: the state of a resting muscle.... relaxation

n. the study of sexual matters, including anatomy, physiology, behaviour, and techniques.... sexology

n. (in physiology) a reciprocal influence exercised by different parts of the body on one another.... sympathy

n. (in physiology) the dissipation of body heat by such processes as the evaporation of sweat from the skin surface.... thermolysis