n. one thousandth of a metre (10?3 m). Symbol: mm.
Blood pressure is recorded by two readings on a sphygmomanometer with the aid of the traditional inflatable cuff. The top pressure is known as the systolic, the bottom as the diastolic. The systolic pressure occurs when the heart contracts, the diastolic when the heart relaxes and the volume of blood is at its lowest. A practitioner interprets the pressure of blood against the wall of the brachial artery in terms of millimetres.
In a healthy young person or middle-aged adult, average systolic pressure is 120, diastolic 80. They are recorded as 120/80. A pressure of 140/90 requires investigation while one of 160/95 is high and demands treatment. Average pressure at 50 is 135/80, over 65 – 165/85. Defined hypertension is a raised pressure on three consecutive readings.
The highest pressure peak is reached in the evening after a day’s work and the lowest, at night. Pressure may rise with stress when the heart responds by beating faster, or fall with physical or mental exhaustion when the heart slows down. Persistent high or low pressure is usually associated with other conditions which may require their own specific treatments: i.e. low – anaemia, high – kidney disease. See: HYPERTENSION. HYPOTENSION. ... blood pressure
While mercury sphygmomanometers are simple, accurate and easily serviced, there is concern about possible mercury toxicity for users, those servicing the devices and the environment. Use of them has already been banned in some European hospitals. Although it may be a few years before they are widely replaced, automated blood-pressure-measuring devices will increasingly be in routine use. A wide variety of ambulatory blood-pressuremeasuring devices are already available and may be ?tted in general practice or hospital settings, where the patient is advised on the technique. Blood-pressure readings can be taken half-hourly – or more often, if required – with little disturbance of the patient’s daily activities or sleep. (See also BLOOD PRESSURE; HYPERTENSION.)... sphygmomanometer
Granulocytes Also known as polymorphonuclear leucocytes (‘polys’), these normally constitute 70 per cent of the white blood cells. They are divided into three groups according to the staining reactions of these granules: neutrophils, which stain with neutral dyes and constitute 65–70 per cent of all the white blood cells; eosinophils, which stain with acid dyes (e.g. eosin) and constitute 3–4 per cent of the total white blood cells; and basophils, which stain with basic dyes (e.g. methylene blue) and constitute about 0·5 per cent of the total white blood cells.
Lymphocytes constitute 25–30 per cent of the white blood cells. They have a clear, non-granular cytoplasm and a relatively large nucleus which is only slightly indented. They are divided into two groups: small lymphocytes, which are slightly larger than erythrocytes (about 8 micrometres in diameter); and large lymphocytes, which are about 12 micrometres in diameter.
Monocytes Motile phagocytic cells that circulate in the blood and migrate into the tissues, where they develop into various forms of MACROPHAGE such as tissue macrophages and KUPFFER CELLS.
Site of origin The granulocytes are formed in the red BONE MARROW. The lymphocytes are formed predominantly in LYMPHOID TISSUE. There is some controversy as to the site of origin of monocytes: some say they arise from lymphocytes, whilst others contend that they are derived from histiocytes – i.e. the RETICULO-ENDOTHELIAL SYSTEM.
Function The leucocytes constitute one of the most important of the defence mechanisms against infection. This applies particularly to the neutrophil leucocytes (see LEUCOCYTOSIS). (See also ABSCESS; BLOOD – Composition; INFLAMMATION; PHAGOCYTOSIS; WOUNDS.)... leucocytes
Once ejaculated during intercourse the spermatozoon travels at a rate of 1·5–3 millimetres a minute and remains mobile for several days after insemination, but quickly loses its potency for fertilisation. As it takes only about 70 minutes to reach the ovarian end of the uterine tube, it is assumed that there must be factors other than its own mobility, such as contraction of the muscle of the womb and uterine tube, that speed it on its way.... spermatozoon
Blood pressure is measured using two values. The systolic pressure – the greater of the two – represents the pressure when blood is pumped from the left VENTRICLE of the heart into the AORTA. The diastolic pressure is the measurement when both ventricles relax between beats. The pressures are measured in millimetres (mm) of mercury (Hg). Despite the grey area between normal and raised blood pressure, the World Health Organisation (WHO) has de?ned hypertension as a blood pressure consistently greater than 160 mm Hg (systolic) and 95 mm Hg (diastolic). Young children have readings well below these, but blood pressure rises with age and a healthy person may well live symptom free with a systolic pressure above the WHO ?gure. A useful working de?nition of hypertension is the ?gure at which the bene?ts of treating the condition outweigh the risks and costs of the treatment.
Between 10 and 20 per cent of the adult population in the UK has hypertension, with more men than women affected. Incidence is highest in the middle-aged and elderly. Because most people with hypertension are symptomless, the condition is often ?rst identi?ed during a routine medical examination, otherwise a diagnosis is usually made when complications occur. Many people’s blood pressure rises when they are anxious or after exercise, so if someone’s pressure is above normal at the ?rst testing, it should be taken again after, say, 10 minutes’ rest, by which time the reading should have settled to the person’s regular level. BP measurements should then be taken on two subsequent occasions. If the pressure is still high, the cause needs to be determined: this is done using a combination of personal and family histories (hypertension can run in families), a physical examination and investigations, including an ECG and blood tests for renal disease.
Over 90 per cent of hypertensive people have no immediately identi?able cause for their condition. They are described as having essential hypertension. In those patients with an identi?able cause, the hypertension is described as secondary. Among the causes of secondary hypertension are:
Lifestyle factors such as smoking, alcohol, stress, excessive dietary salt and obesity.
Diseases of the KIDNEYS.
Pregnancy (ECLAMPSIA).
Various ENDOCRINE disorders – for example, PHAEOCHROMOCYTOMA, CUSHING’S DISEASE, ACROMEGALY, thyrotoxicosis (see under THYROID GLAND, DISEASES OF).
COARCTATION OF THE AORTA.
Drugs – for example, oestrogen-containing oral contraceptives (see under CONTRACEPTION), ANABOLIC STEROIDS, CORTICOSTEROIDS, NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).
Treatment People with severe hypertension may need prompt admission to hospital for urgent investigation and treatment. Those with a mild to moderate rise in blood pressure for which no cause is identi?able should be advised to change their lifestyle: smokers should stop the habit, and those with high alcohol consumption should greatly reduce or stop their drinking. Obese people should reduce their food consumption, especially of animal fats, and take more exercise. Everyone with hypertension should follow a low-salt diet and take regular exercise. Patients should also be taught how to relax, which helps to reduce blood pressure and, if they have a stressful life, working patterns should be modi?ed if possible. If these lifestyle changes do not reduce a person’s blood pressure su?ciently, drugs to achieve this will be needed. A wide range of anti-hypertensive drugs are available on prescription.
A ?rst-line treatment is one of the THIAZIDES, e?ective at a low dosage and especially useful in the elderly. Beta blockers (see BETAADRENOCEPTOR-BLOCKING DRUGS), such as oxprenolol, acebutol or atenolol, are also ?rst-line treatments. ACE inhibitors (see ANGIOTENSIN-CONVERTING ENZYME (ACE) INHIBITORS) and CALCIUM-CHANNEL BLOCKERS can be used if the ?rst-line choices are not e?ective. The drug treatment of hypertension is complex, and sometimes various drugs or combinations of drugs have to be tried to ?nd what regimen is e?ective and suits the patient. Mild to moderate hypertension can usually be treated in general practice, but patients who do not respond or have complications will normally require specialist advice. Patients on anti-hypertensive treatments require regular monitoring, and, as treatment may be necessary for several years, particular attention should be paid to identifying sideeffects. Nevertheless, e?ective treatment of hypertension does enable affected individuals to live longer and more comfortable lives than would otherwise be the case. Older people with moderately raised blood pressure are often able to live with the condition, and treatment with anti-hypertensive drugs may produce symptoms of HYPOTENSION.
In summary, hypertension is a complex disorder, with di?erent patients responding di?erently to treatment. So the condition sometimes requires careful assessment before the most e?ective therapy for a particular individual is identi?ed, and continued monitoring of patients with the disorder is advisable.
Complications Untreated hypertension may eventually result in serious complications. People with high blood pressure have blood vessels with thickened, less ?exible walls, a narrowed LUMEN and convoluted shape. Sometimes arteries become rigid. ANEURYSM may develop and widespread ATHEROMA (fat deposits) is apparent in the arterial linings. Such changes adversely affect the blood supply to body tissues and organs and so damage their functioning. Patients suffer STROKE (haemorrhage from or thrombosis in the arteries of the BRAIN) and heart attacks (coronary thrombosis
– see HEART, DISEASES OF). Those with hypertension may suffer damage to the retina of the EYE and to the OPTIC DISC. Indeed, the diagnosis of hypertension is sometimes made during a routine eye test, when the doctor or optician notices changes in the retinal arteries or optic disc. Kidney function is often affected, with patients excreting protein and excessive salt in their urine. Occasionally someone with persistent hypertension may suffer an acceleration of damage to the blood vessels – a condition described as ‘malignant’ hypertension, and one requiring urgent hospital treatment.
Hypertension is a potentially dangerous disease because it develops into a cycle of self-perpetuating damage. Faulty blood vessels lead to high blood pressure which in turn aggravates the damage in the vessels and thus in the tissues and organs they supply with blood; this further raises the affected individual’s blood pressure and the pathological cycle continues.... hypertension
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
Sensory These carry signals to the central nervous system (CNS) – the BRAIN and SPINAL CORD – from sensory receptors. These receptors respond to di?erent stimuli such as touch, pain, temperature, smells, sounds and light.
Motor These carry signals from the CNS to activate muscles or glands.
Interneurons These provide the interconnecting ‘electrical network’ within the CNS.
Structure Each neurone comprises a cell body, several branches called dendrites, and a single ?lamentous ?bre called an AXON. Axons may be anything from a few millimetres to a metre long; at their end are several branches acting as terminals through which electrochemical signals are sent to target cells, such as those of muscles, glands or the dendrites of another axon.
Axons of several neurones are grouped
together to form nerve tracts within the brain or spinal cord or nerve-?bres outside the CNS. Each nerve is surrounded by a sheath and contains bundles of ?bres. Some ?bres are medullated, having a sheath of MYELIN which acts as insulation, preventing nerve impulses from spreading beyond the ?bre conveying them.
The cellular part of the neurones makes up the grey matter of the brain and spinal cord – the former containing 600 million neurones. The dendrites meet with similar outgrowths from other neurones to form synapses. White matter is the term used for that part of the system composed of nerve ?bres.
Functions of nerves The greater part of the bodily activity originates in the nerve cells (see NERVE). Impulses are sent down the nerves which act simply as transmitters. The impulse causes sudden chemical changes in the muscles as the latter contract (see MUSCLE). The impulses from a sensory ending in the skin pass along a nerve-?bre to affect nerve cells in the spinal cord and brain, where they are perceived as a sensation. An impulse travels at a rate of about 30 metres (100 feet) per second. (See NERVOUS IMPULSE.)
The anterior roots of spinal nerves consist of motor ?bres leading to muscles, the posterior roots of sensory ?bres coming from the skin. The terms, EFFERENT and AFFERENT, are applied to these roots, because, in addition to motor ?bres, ?bres controlling blood vessels and secretory glands leave the cord in the anterior roots. The posterior roots contain, in addition to sensory ?bres, the nerve-?bres that transmit impulses from muscles, joints and other organs, which among other neurological functions provide the individual with his or her
proprioceptive faculties – the ability to know how various parts of the body are positioned.
The connection between the sensory and motor systems of nerves is important. The simplest form of nerve action is that known as automatic action. In this, a part of the nervous system, controlling, for example, the lungs, makes rhythmic discharges to maintain the regular action of the respiratory muscles. This controlling mechanism may be modi?ed by occasional sensory impressions and chemical changes from various sources.
Re?ex action This is an automatic or involuntary activity, prompted by fairly simple neurological circuits, without the subject’s consciousness necessarily being involved. Thus a painful pinprick will result in a re?ex withdrawal of the affected ?nger before the brain has time to send a ‘voluntary’ instruction to the muscles involved.
Voluntary Actions are more complicated than re?ex ones. The same mechanism is involved, but the brain initially exerts an inhibitory or blocking e?ect which prevents immediate re?ex action. Then the impulse, passing up to the cerebral hemispheres, stimulates cellular activity, the complexity of these processes depending upon the intellectual processes involved. Finally, the inhibition is removed and an impulse passes down to motor cells in the spinal cord, and a muscle or set of muscles is activated by the motor nerves. (Recent advances in magnetic resonance imaging (MRI) techniques have provided very clear images of nerve tracts in the brain which should lead to greater understanding of how the brain functions.) (See BRAIN; NERVOUS SYSTEM; SPINAL CORD.)... neuron(e)
Causes: chronic catarrh with obstruction of the Eustachian tubes of dietetic origin. Starchy foods should be severely restricted. The ear is clogged with a sticky fluid usually caused by enlarged adenoids blocking the ventilation duct which connects the cavity with the back of the throat.
Conventional treatment consists of insertion of ‘grommets’ – tiny flanged plastic tubes about one millimetre long – which are inserted into the eardrum, thus ensuring a free flow of air into the cavity.
Fluid usually disappears and hearing returns to normal.
Tre atme nt. Underlying cause treated – adenoids, tonsils, etc. Sinus wash-out with Soapwort, Elderflowers, Mullein or Marshmallow tea. Internal treatment with anti-catarrhals to disperse. Alternatives:– German Chamomile tea. (Traditional German).
Teas. Boneset, Cayenne, Coltsfoot, Elderflowers, Eyebright, Hyssop, Marshmallow leaves, Mullein, Mint, Yarrow.
Powders. Combine: Echinacea 2; Goldenseal quarter; Myrrh quarter; Liquorice half. Dose: 500mg (two 00 capsules or one-third teaspoon), thrice daily.
Tinctures. Combine: Echinacea 2; Yarrow 1; Plantain 1. Drops: Tincture Capsicum. Dose: 1-2 teaspoons thrice daily.
Topical. Castor oil drops, with cotton wool ear plugs, Oils of Garlic or Mullein. If not available, use Almond oil. Hopi Indian Ear Candles for mild suction and to impart a perceptible pressure regulation of sinuses and aural fluids.
Diet. Gluten-free diet certain. No confectionery, chocolate, etc. Salt-free. Low-starch. Milk-free. Abundance of fruits and raw green salad materials. Supplements. Vitamins A, B-complex, C. E. ... otitis media – glue ear
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