Illustrated Medical Dictionary; Essential A-Z Quick Reference to over 5,500 Medical Terms - Dorling Kindersley DK Publishing

612 Pages·2016·38.02 MB·English

by  The British Medical Association, (BMA), (2007)

The British
Medical Association
ILLUSTRATED
MEDICAL
DICTIONARY
CORONARY ARTERY coronary Any structure that encircles like
a crown. The term usually refers to the
vSeunpae rciaovr a Aorta cLoerfot nmaaryin caolsroo nsaorym aerttiemrieess eunsceidrc lainsg ath en ohnemaret.d Iitc aisl
artery term for a heart attack (see myocardial
Pulmonary Left infarction).
veins circumflex coronary artery Either of the 2 main
artery arteries that supply the tissues of the
heart with oxygen-rich blood. These
arteries, known as the left and right main
Left coronary arteries, arise directly from the
Right anterior aorta. The term coronary artery is also
m
c
aoratreionrnyary daretescryending aopffp flrioemd ttoh ea nmy aoifn t hcoer aorntaeryie asr theraite sb,r asnuch
Coronary as the left circumflex artery and the left
vein anterior descending artery. Blockage of a
Inferior Descending coronary artery as a result of athero-
vena cava aorta sclerosis can lead to myocardial infarction.
(See also coronary artery disease.)
Essential A–Z quick reference
to over 5,500 medical terms
The British
Medical Association
ILLUSTRATED
MEDICAL
DICTIONARY
A Dorling Kindersley Book
ABDOMEN ABDOMINAL SWELLING
A intake, eating unwisely, or an attack of
diarrhoea. Pain in the lower abdomen
is common during menstruation but is
occasionally due to a gynaecological
disorder such as endometriosis. Cystitis
is a common cause of pain or discom-
fort in the abdomen. Bladder distension
A asls oa craeussuelt a obfd oumrininaaryl poabins.t ruction may
abdomen The region of the body be- Abdominal colic is pain that occurs
tween the chest and the pelvis. The every few minutes as one of the internal
abdominal cavity is bounded by the ribs organs goes into muscular spasm in an
and diaphragm above, and by the pelvis attempt to overcome an obstruction
below, with the spine and abdominal such as a stone or an area of inflamma-
muscles forming the back, side, and tion. The attacks of colic may become
front walls. It contains the liver, stom- more severe and may be associated
ach, intestines, spleen, pancreas, and with vomiting (see abdomen, acute).
kidneys. In the lower abdomen, enclosed Peptic ulcer often produces recurrent
by the pelvis, are the bladder, rectum, gnawing pain. Other possible causes of
and, in women, the uterus and ovaries. abdominal pain are infection, such as
pyelonephritis, and ischaemia (lack of
ABDOMEN blood supply), as occurs when a volvu-
lus (twisting of the intestine) obstructs
Stomach blood vessels. Tumours affecting an
Liver abdominal organ can cause pain. Abdo-
minal pain can also result from anxiety.
For mild pain, a wrapped hot-water
Large bottle is often effective. Pain due to
intestine A
abredao omfen pbye ptfioco udl ceorr cabny btea ktienmg poarnatraiclyid r edlireuvgesd.
Small Abdominal pain that is not relieved by
intestine vomiting, persists for more than 6 hours,
Rectum oinrg i sr eaqsusoirceisa tuedrg ewnith m sewdeiactailn ga toter nfatiionnt-.
Urgent attention is also necessary if
pain is accompanied by persistent vom-
abdomen, acute Persistent, severe ab- iting, vomiting of blood, or passing of
dominal pain of sudden onset, usually bloodstained or black faeces. Unex-
associated with spasm of the abdomi- plained weight loss or changes in bowel
nal muscles, vomiting, and fever. habits should always be investigated.
The most common cause of an acute Investigation of abdominal pain may
abdomen is peritonitis. Other causes include the use of imaging tests such as
include appendicitis, abdominal injury, ultrasound scanning, and endoscopic
perforation of an internal organ due to examination in the form of gastroscopy,
disorders such as peptic ulcer or diver- colonoscopy, or laparoscopy.
ticular disease. Acute abdominal pain abdominal swelling Enlargement of
commonly begins as a vague pain in the the abdomen. Abdominal swelling is a
centre but then becomes localized. natural result of obesity and growth of
An acute abdomen requires urgent the uterus during pregnancy. Wind in the
medical investigation that may involve stomach or intestine may cause uncom-
a laparoscopy or a laparotomy. Treat- fortable, bloating distension of the
ment depends on the underlying cause. abdomen. Some women experience ab-
abdominal pain Discomfort in the ab- dominal distension due to temporary
domen. Mild abdominal pain is common water retention just before menstrua-
and is often due to excessive alcohol tion. Other causes may be more serious.
4
ABDOMINAL THRUST ABSCESS
For instance, ascites (accumulation of ABO blood groups See blood groups. A
fluid between organs) may be a symp- abortifacient An agent that causes abor-
tom of cancer or disease of the heart, tion. In medical practice, abortion is
kidneys, or liver; swelling may also be induced using prostaglandin drugs,
due to intestinal obstruction (see intes- often given as vaginal pessaries.
tine, obstruction of) or an ovarian cyst. abortion In medical terminology, either
Diagnosis of the underlying cause may spontaneous abortion (see miscarriage)
involve abdominal X-rays, ultrasound or medically induced termination of
scanning, laparotomy, or laparoscopy. In pregnancy (see abortion, induced).
ascites, some fluid between organs may abortion, induced Medically induced
be drained for examination. termination of pregnancy. Abortion may
abdominal thrust A first-aid treatment be performed if continuation of the
for choking, in which sharp upward pres- pregnancy would risk the woman’s life,
sure is applied to the upper abdomen if the mental or physical health of the
to dislodge a foreign body obstructing woman or her existing children is at
the airway. The technique is also known risk, or if there is a substantial risk of
as the Heimlich manoeuvre. handicap to the baby.
abdominal X-ray An X-ray examina- Depending on the stage of pregnancy,
tion of the abdominal contents. X-rays termination may be induced by using
can show whether any organ is enlarged drugs or by the surgical technique of
and can detect swallowed foreign bod- vacuum suction curettage, under either
ies in the digestive tract. They also show a general or local anaesthetic, during
patterns of fluid and gas: distended which the fetal and placental tissues are
loops of bowel containing fluid often removed. Complications are rare.
indicate an obstruction (see intestine, abrasion Also called a graze, a wound
obstruction of); gas outside the intestine on the skin surface that is caused by
indicates intestinal perforation. scraping or rubbing.
Calcium, which is opaque to X-rays, is abrasion, dental The wearing away of
present in most kidney stones (see tooth enamel, often accompanied by the
calculus, urinary tract) and in some erosion of dentine (the layer beneath
gallstones and aortic aneurysms; these the enamel) and cementum (the bone-
can sometimes be detected on an like tissue that covers the tooth root),
abdominal X-ray. usually through too-vigorous brushing.
abducent nerve The 6th cranial nerve. Abraded areas are often sensitive to
It supplies the lateral rectus muscle of cold or hot food or drink, and a desensi-
each eye, which is responsible for mov- tizing toothpaste and/or protection with
ing the eyeball outwards. The nerve a bonding (see bonding, dental) agent or
originates in the pons (part of the brain- filling may be needed.
stem) and passes along the base of the abreaction In psychoanalysis, the pro-
brain, entering the back of the eye socket cess of becoming consciously aware of
through a gap between the skull bones. repressed (buried) thoughts and feelings.
abduction Movement of a limb away In Freudian theory, abreaction ideally
from the central line of the body, or of a occurs by way of catharsis.
digit away from the axis of a limb. Mus- abscess A collection of pus formed as a
cles that carry out this movement are result of infection by microorganisms,
called abductors. (See also adduction.) usually bacteria. Abscesses may develop
ablation Removal or destruction of dis- in any organ and in the soft tissues
eased tissue by excision (cutting away), beneath the skin in any area. Common
cryosurgery (freezing), radiotherapy, dia- sites include the armpit, breast (see
thermy (burning), or laser treatment. breast abscess), groin, and gums (see
abnormality A physical deformity or abscess, dental). Rarer sites include the
malformation, a behavioural or mental liver (see liver abscess) and the brain
problem, or a variation from normal in (see brain abscess).
the structure or function of a cell, tis- Common bacteria, such as staphylo-
sue, or organ in the body. cocci, are the usual cause of abscesses,
5
ABSCESS, DENTAL ACANTHOSIS NIGRICANS
A a
thltehmo,u gahn df uanmgaole bianefecatrieo nasn ciamnp ocratuasnet ABSCESS, DENTAL
cause of liver abscesses (see amoebia- Enamel Decay
sis). Infectious organisms usually reach
tinhteeyr npael noertgratnes tvisas uthees bulnodoedrs ttrheaem s,k oinr Dentine Gum
through a wound.
An abscess may cause pain, depending Pulp
on where it occurs. Most larger absces- Blood
ses cause fever, sweating, and malaise. vessel
Those that are close to the skin often Nerve
cause obvious redness and swelling.
Antibiotics, antifungal drugs, or amoe- Jawbone
bicides are usually prescribed as Abscess
appropriate. Most abscesses also need
to be drained (see drain, surgical), and
in some cases a tube may be left in
place to allow continuous drainage.
Some abscesses burst and drain spon- An abscess in a periodontal pocket can
taneously. Occasionally, an abscess usually be treated by the dentist scrap-
within a vital organ damages enough ing away infected material.
surrounding tissue to cause permanent absence In medical terms, a temporary
loss of normal function, or even death. loss or impairment of consciousness
abscess, dental A pus-filled sac in the that occurs in some forms of epilepsy,
tissue around the root of a tooth. An typically generalized absence (petit
abscess may occur when bacteria mal) seizures in childhood.
invade the pulp (the tissues in the cen- absorption The process by which flu-
tral cavity of a tooth) as a result of ids or other substances are taken up by
dental caries, which destroys the tooth’s body tissues. The term is commonly
enamel and dentine, allowing bacteria applied to the uptake of the nutrients
to reach the pulp. Bacteria can also gain from food into blood and lymph from
access to the pulp when a tooth is the digestive tract. The major site of
injured. The infection in the pulp then absorption is the small intestine, which
spreads into the surrounding tissue to is lined with microscopic finger-like
form an abscess. Abscesses can also projections called villi (see villus). The
result from periodontal disease, in which villi greatly increase the surface area of
bacteria accumulate in pockets that the intestine, thereby increasing the
form between the teeth and gums. rate of absorption.
The affected tooth aches or throbs, acanthosis nigricans A rare condition
and biting or chewing is usually in which thickened dark patches of skin
extremely painful. The gum around the appear in the groin, armpits, neck, and
tooth is tender and may be red and other skin folds. The condition may
swollen. An untreated abscess eventu- occur in young people as a genetic dis-
ally erodes a sinus (channel) through order or as the result of an endocrine
the jawbone to the gum surface, where disorder such as Cushing’s syndrome. It
it forms a swelling known as a gumboil. also occurs in people with carcinomas
As the abscess spreads, the glands in of the lung and other organs.
the neck and the side of the face may Pseudoacanthosis nigricans is a much
become swollen, and fever may develop. more common condition, usually seen
Treatment may consist of draining the in dark-complexioned people who are
abscess, followed by root-canal treat- overweight. In this form, the skin in fold
ment of the affected tooth, but in some areas is both thicker and darker than the
cases extraction of the tooth is neces- surrounding skin, and there is usually
sary. Antibiotics are prescribed if the excessive sweating in affected areas. The
infection has spread beyond the tooth. condition may improve with weight loss.
6
ACARBOSE ACETYLCHOLINESTERASE INHIBITORS
acarbose A drug that is used to treat more difficult and results in a form of A
type 2 diabetes mellitus. Acarbose acts longsightedness called presbyopia.
on enzymes in the intestines, inhibiting acebutolol A beta-blocker drug used to
the digestion of starch and therefore treat hypertension, angina pectoris, and
slowing the rise in blood glucose levels certain types of arrhythmia in which the
after a carbohydrate meal. heart beats too rapidly.
accessory nerve The 11th cranial nerve. ACE inhibitor drugs A group of vaso-
Unlike the other cranial nerves, most of dilator drugs used to treat heart failure,
the accessory nerve originates from the hypertension, and diabetic nephropathy.
spinal cord. The small part of the nerve ACE (angiotensin converting enzyme) in-
that originates from the brain supplies hibitors are often prescribed with other
many muscles of the palate, pharynx drugs such as diuretic drugs or beta-
(throat), and larynx (voice box). Damage blocker drugs. Possible side effects
to this part of the nerve may cause diffi- include nausea, loss of taste, headache,
culty in speaking and swallowing. The dizziness, and dry cough.
spinal part of the nerve supplies large acetaminophen An analgesic drug
muscles of the neck and back, notably more commonly known as paracetamol.
the sternomastoid and trapezius. Dam- acetazolamide A drug that is used in
age to the spinal fibres of the nerve the treatment of glaucoma and, occa-
paralyses these muscles. sionally, to prevent or treat symptoms
accidental death Death that occurs as of mountain sickness. Possible adverse
a direct result of an accident. A high pro- effects include lethargy, nausea, diar-
portion of deaths in young adults, rhoea, and impotence.
particularly among males, are acciden- acetic acid The colourless, pungent, org-
tal. Many of these deaths are due to anic acid that gives vinegar its sour
road traffic accidents, drowning, or drug taste. In medicine, acetic acid is an
overdose. Falls in the home and burning ingredient of antiseptic gels that are
or asphyxiation due to fire are common used for certain vaginal infections.
causes of accidental death in elderly acetylcholine A type of neurotransmit-
people. Fatal accidents at work have ter (a chemical that transmits messages
become less common with the intro- between nerve cells or between nerve
duction of effective safety measures. and muscle cells). Acetylcholine is the
accommodation Adjustment, especially neurotransmitter found at all nerve-
the process by which the eye adjusts muscle junctions and at many other
itself to focus on near objects. At rest, sites in the nervous system. The actions
the eye is focused for distant vision, of acetylcholine are called cholinergic
when its lens is thin and flat. To make actions, and these can be blocked by
focusing on a nearer object possible, anticholinergic drugs.
the ciliary muscle of the eye contracts, acetylcholinesterase inhibitors A
which reduces the pull on the outer rim group of drugs that are used in the
of the lens, allowing it to become thicker treatment of mild to moderate dementia
and more convex. due to Alzheimer’s disease, in which
With age, the lens loses its elasticity. there is a deficiency of the neuro-
This makes accommodation more and transmitter acetylcholine in the brain.
ACCOMMODATION
Light rays from Point of Light rays from Point of
near object focus distant object focus
Rounded
Ciliary lens bends Ciliary Flattened
muscle the light muscle lens
NEAR FOCUS DISTANT FOCUS
7
ACETYLCYSTEINE ACID–BASE BALANCE
A Drugs such as donepezil and rivastig- Violent stretching of the tendon can
mine work by blocking the action of cause it to rupture; in such cases, surgi-
acetylcholinesterase, the enzyme in the cal repair may be necessary.
brain responsible for the breakdown of achlorhydria Absence of stomach acid
acetylcholine. This raises acetylcholine secretions. This may be due to chronic
levels, and, in half of all patients, the atrophic gastritis or to an absence or
drugs slow the rate of progression of malfunction of acid-producing parietal
dementia. They have no effect on cells in the stomach lining. Achlorhydria
dementia due to other causes, such as may not produce symptoms but is asso-
stroke or head injury, however. Com- ciated with stomach cancer, however,
mon side effects include nausea, and is a feature of pernicious anaemia
dizziness, and headache. Rarely, diffi- (see anaemia, megaloblastic).
culty in passing urine may occur. achondroplasia A rare genetic disor-
acetylcysteine A drug used in the treat- der of bone growth that leads to short
ment of paracetamol overdose and as a stature. The condition is caused by a
mucolytic drug to loosen sputum. When dominant gene (see genetic disorders)
the drug is taken in large doses, vomiting but often arises as a new mutation. The
or rash may occur as rare side effects. long bones of the arms and legs are
achalasia A rare condition of unknown affected mainly. The cartilage that links
cause in which the muscles at the lower each bone to its epiphysis (the growing
end of the oesophagus and the sphinc- area at its tip) is converted to bone too
ter (valve) between the oesophagus and early, preventing further limb growth.
the stomach fail to relax to let food into Those affected have short limbs, a well-
the stomach after swallowing. As a developed trunk, and a head of normal
result, the lowest part of the oesopha- size except for a protruding forehead.
gus is narrowed and becomes blocked aciclovir An antiviral drug that can be
with food, while the part above widens. taken by mouth, used topically, or given
Symptoms include difficulty and pain intravenously to reduce the severity of
with swallowing and pain in the lower viral infections including herpes simplex
chest and upper abdomen. and herpes zoster. Local adverse reac-
A barium swallow (a type of barium tions commonly occur after topical use.
X-ray examination) and gastroscopy may Other side effects are uncommon but
be performed to investigate achalasia. can include nausea and vomiting.
Oesophageal dila- acid A substance defined as a donor of
ACHILLES TENDON tation allows the hydrogen ions (hydrogen atoms with
mCaulsf cle oweidsoenpehda gufosr tolo bneg puolessi,t ivweh elne cmtrixceadl cwhaitrhg eosr) . dAicsisdo lmveodle icn-
periods. Surgery to water, split up to release their con-
cut some of the stituent ions; all acids release hydrogen
muscles at the sto- as the positive ion. (See also acid–base
mach entrance may balance; alkali.)
be necessary. acid–base balance A combination of
Achilles Achilles tendon mechanisms that ensures that the body’s
tendon The tendon that fluids are neither too acid nor too alka-
raises the heel. line (alkalis are also called bases).
The Achilles ten- The body has three mechanisms for
don is formed from maintaining normal acid–base balance:
the calf muscles buffers, breathing, and the activities of
Heel (gastrocnemius, the kidneys. Buffers are substances in
soleus, and plan- the blood that neutralize acid or alka-
tar muscles) and line wastes. Rapid breathing results in
is attached to the the blood becoming less acidic; slow
calcaneus (heel-bone). Minor injuries to breathing has the opposite effect. The
the Achilles tendon are common and kidneys regulate the amounts of acid or
can result in inflammation (tendinitis). alkaline wastes in the urine.
8
ACIDOSIS ACOUSTIC NEUROMA
Disturbances of the body’s acid–base Acne develops in areas of skin with a A
balance result in either acidosis (exces- high concentration of sebaceous glands,
sive blood acidity) or alkalosis (excessive mainly the face, centre of the chest,
blood alkalinity). upper back, shoulders, and around the
acidosis A disturbance of the body’s neck. Milia (whiteheads), comedones
acid–base balance in which there is an (blackheads), nod-
accumulation of acid or loss of alkali ules (firm swel- ACNE
(base). There are 2 types of acidosis: lings beneath the Sebaceous Inflamed skin
m
Oetnaeb ofloicrm an do fr esmpeirtatboorlyi.c acidosis is (slkairng)e, r, aflnudid -fciyllsetds gland Plug Pus
ketoacidosis, which occurs in uncon- swellings) are the Hair
trolled diabetes mellitus and starvation. most commonly
Metabolic acidosis may also be caused occurring spots.
by loss of bicarbonate (an alkali) as a Some, particularly
result of severe diarrhoea. In kidney fail- cysts, leave scars
ure, there is insufficient excretion of after they heal.
acid in the urine. There is no inst-
Respiratory acidosis occurs if breathing ant cure for acne,
fails to remove enough carbon dioxide but washing the
from the lungs. The excess carbon di- affected areas at
oxide remains in the bloodstream, least twice daily
where it dissolves to form carbonic acid. may help to keep
Impaired breathing leading to respira- it under control. ACNE SPOT
tory acidosis may be due to chronic Topical drug treat-
obstructive pulmonary disease (see pul- ments, such as benzoyl peroxide or
monary disease, chronic obstructive), retinoic acid, unblock the pores and
bronchial asthma, or airway obstruction. promote healing. Ultraviolet light can
acid reflux Regurgitation of acidic fluid be beneficial. If topical treatment has
from the stomach into the oesophagus failed, oral drug treatment with anti-
due to inefficiency of the muscular valve biotics, hormones, or isotretinoin may be
at the lower end of the oesophagus. given. Acne improves slowly over time,
Also known as gastro-oesophageal often clearing up by the end of the
reflux disease (GORD), acid reflux may teenage years.
inflame the oesophagus, resulting in acoustic nerve The part of the vestibu-
heartburn due to oesophagitis. It may locochlear nerve (the 8th cranial nerve)
occur in pregnancy and often affects that is concerned with hearing. It is also
overweight people. known as the auditory nerve.
acne A chronic skin disorder caused by acoustic neuroma A rare, noncancer-
inflammation of the hair follicles and ous tumour arising from supporting
sebaceous glands in the skin. The most cells that surround the 8th cranial nerve
common type is acne vulgaris, which (see acoustic nerve), usually within the
almost always develops during puberty. internal auditory meatus (the canal in
Acne spots are caused by the obstruc- the skull through which the nerve pass-
tion of hair follicles by sebum (the oily es from the inner ear to the brain).
substance secreted by the sebaceous Usually, the cause of an acoustic neuro-
glands). Bacteria multiply in the follicle, ma is unknown. However, tumours that
causing inflammation. The change in affect the nerves on both sides of the
sebum secretion at puberty seems to be head simultaneously may be part of a
linked with increased levels of androgen condition known as neurofibromatosis.
hormones (male sex hormones). Acoustic neuroma can cause deafness,
Acne may be brought on or aggravated tinnitus, loss of balance, and pain in the
by drugs such as corticosteroids and face and the affected ear.
androgens. Exposure to certain chemi- Diagnosis is made by hearing tests fol-
cals and oils in the workplace can also lowed by X-rays, CT scanning, or MRI.
cause a type of acne. Surgery may be needed, but treatment
9
ACROCYANOSIS ACTINOMYCOSIS
A with radiotherapy to shrink the tumour acroparaesthesia A medical term used
is also effective. to describe tingling in the fingers or
acrocyanosis A circulatory disorder in toes (see pins-and-needles).
which the hands and feet turn blue, may ACTH The common abbreviation for
become cold, and sweat excessively. adrenocorticotrophic hormone (also
Acrocyanosis is caused by spasm of the called corticotrophin). ACTH is produced
small blood vessels and is often aggra- by the anterior pituitary gland and stim-
vated by cold weather. It is related to ulates the adrenal cortex (outer layer of
Raynaud’s disease. the adrenal glands) to release various
acrodermatitis enteropathica A rare corticosteroid hormones, most impor-
inherited disorder in which areas of the tantly hydrocortisone (cortisol) but also
skin (most commonly the fingers, toes, aldosterone and androgen hormones.
scalp, and the areas around the anus ACTH production is controlled by a
and mouth) are reddened, ulcerated, and feedback mechanism involving both the
covered with pustules. Acrodermatitis hypothalamus and the level of hydro-
enteropathica is due to an inability to cortisone in the blood. ACTH levels
absorb enough zinc from food. Zinc increase in response to stress, emotion,
supplements usually help. injury, infection, burns, surgery, and
acromegaly A rare disease characterized decreased blood pressure.
by abnormal enlargement of the skull, A tumour of the pituitary gland can
jaw, hands, feet, and also of the internal cause excessive ACTH production which
organs. It is caused by excessive secre- leads to overproduction of hydrocorti-
tion of growth hormone from the sone by the adrenal cortex, resulting in
anterior pituitary gland at the base of Cushing’s syndrome. Insufficient ACTH
the brain and is the result of a pituitary production results in decreased produc-
tumour. A tumour that develops before tion of hydrocortisone, causing low
puberty results in gigantism. Acromeg- blood pressure. Synthetic ACTH is occa-
aly is diagnosed by measuring blood sionally given by injection to treat
levels of growth hormone, followed by arthritis or allergy.
CT scanning or MRI. actin A protein involved in muscle con-
acromioclavicular joint The joint that traction, in which microscopic filaments
lies between the outer end of the cla- of actin and another protein, myosin,
vicle (collarbone) and the acromion slide in between each other.
(the bony prominence at the top of the acting out Impulsive actions that may
scapula (shoulderblade). reflect unconscious wishes. The term is
most often used by psychotherapists
ACROMIOCLAVICULAR JOINT to describe behaviour during analysis
Clavicle Acromioclavicular wrehpeonr tsth ef apnattaiseinets ,“ awctiss hoeust,” roart hebre ltiheafsn.
joint Acting out can also occur as a reaction
to frustrations encountered in everyday
Acromion life, often taking the form of antisocial,
aggressive behaviour.
Scapula actinic Pertaining to changes caused by
the ultraviolet rays in sunlight, as in
actinic dermatitis (inflammation of the
Humerus skin) and actinic keratosis (roughness
and thickening of the skin).
actinomycosis An infection caused by
ACTINOMYCES ISRAELII or related actino-
acromion A bony prominence at the mycete bacteria. The most common
top of the scapula (shoulderblade). The form of actinomycosis affects the jaw
acromion articulates with the end of area. A painful swelling appears and
the clavicle (collarbone) to form the pus discharges through small openings
acromioclavicular joint. that develop in the skin. Another form
10
ACUITY, VISUAL ADENOCARCINOMA
of actinomycosis affects the pelvis in the corticosteroid hormones hydrocorti- A
women, causing lower abdominal pain sone and aldosterone, normally produced
and bleeding between periods. This by the adrenal cortex (the outer part of
form was associated with a type of IUD, the adrenal glands). Excessive amounts
no longer in use, that did not contain of ACTH are secreted by the pituitary
copper. Rarely, forms of the disorder gland in an attempt to increase output
affect the appendix or lung. Actinomy- of the corticosteroid hormones. Secre-
cosis is treated with antibiotics. tion and activity of another hormone,
acuity, visual See visual acuity. melanocyte stimulating hormone (MSH),
acupressure A derivative of acupunc- is also increased.
ture in which pressure is applied Addison’s disease can be caused by
instead of needles. any disease that destroys the adrenal
acupuncture A branch of Chinese med- cortices. The most common cause is an
icine in which needles are inserted into autoimmune disorder in which the
a patient’s skin as therapy for various immune system produces antibodies
disorders or to induce anaesthesia. that attack the adrenal glands.
Traditional Chinese medicine main- Symptoms generally develop gradu-
tains that the chi (life-force) flows ally over months or years, and include
through the body along channels called tiredness, weakness, abdominal pain,
meridians. A blockage in one or more of and weight loss. Excess MSH may cause
these meridians is thought to cause ill darkening of the skin in the creases of
health. Acupuncturists aim to restore the palms, pressure areas of the body,
health by inserting needles at appropri- and the mouth. Acute episodes, called
ate sites along the affected meridians. Addisonian crises, brought on by infec-
The needles are stimulated by rotation tion, injury, or other stresses, can also
or by an electric current. Acupuncture occur. The symptoms of these include
has been used successfully as an anaes- extreme muscle weakness, dehydration,
thetic for surgical procedures and to hypotension (low blood pressure), con-
provide pain relief after operations and fusion, and coma. Hypoglycaemia (low
for chronic conditions. blood glucose) also occurs.
acute A term often used to describe a Life-long corticosteroid drug treatment
disorder or symptom that develops sud- is needed. Treatment of Addisonian
denly. Acute conditions may or may not crises involves rapid infusion of saline
be severe, and they are usually of short and glucose, and supplementary doses
duration. (See also chronic.) of corticosteroid hormones.
Adam’s apple A projection at the front adduction Movement of a limb towards
of the neck, just beneath the skin, that the central line of the body, or of a digit
is formed by a prominence on the thy- towards the axis of a limb. Muscles that
roid cartilage, which is part of the larynx carry out this movement are often called
(voice box). The Adam’s apple enlarges adductors. (See also abduction.)
in males at puberty. adenitis Inflammation of lymph nodes.
ADD The abbreviation for attention defi- Cervical adenitis (swelling and tender-
cit disorder, more commonly known as ness of the lymph nodes in the neck)
attention deficit hyperactivity disorder. occurs in certain bacterial infections,
addiction Dependence on, and craving especially tonsillitis, and glandular fever
for, a particular drug, for example alco- (see infectious mononucleosis). Mesen-
hol, diazepam (a tranquillizer), or heroin. teric lymphadenitis is inflammation of
Reducing or stopping intake of the drug the lymph nodes inside the abdomen
may lead to characteristic physiological and is usually caused by viral infection.
or psychological symptoms (see with- Treatment of adenitis may include anal-
drawal syndrome), such as tremor or gesic drugs, and antibiotic drugs if there
anxiety. (See also alcohol dependence; is a bacterial infection.
drug dependence.) adenocarcinoma The technical name
Addison’s disease A rare chronic dis- for a cancer of a gland or glandular tis-
order in which there is a deficiency of sue, or for a cancer in which the cells
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