Bma Illustrated Medical Dictionary

defence against local infection. The

position of an individual’s appendix

partly determines the set of symptoms

produced by acute appendicitis(inflam-

mation of the appendix).

appetiteA desire for food; a pleasant

sensation felt in anticipation of eating.

Appetite, which is regulated by 2 parts

of the brain(the hypothalamus and the

cerebral cortex), is learned by enjoying

a variety of foods that smell, taste, and

look good. It combines with hungerto

ensure that the right amount of a wide

range of foods is eaten to stay healthy.

(See also appetite,loss of.)

appetite, loss ofLoss of appetite is

usually temporary and due to an emo-

tional upset or minor illness.Persistent

loss of appetite may have a more seri-

ous underlying cause, such as chronic

infection or cancer.

appetite stimulantsVarious tonics and

remedies traditionally prescribed to

stimulate the appetite. None are proven

to be effective. Some drugs such as cor-

ticosteroidsmay stimulate the appetite

when used to treat unrelated disorders.

appetite suppressantsA group of drugs

that reduce the desire to eat. Appetite

suppressants may be used in the treat-

ment of severe obesity, along with diet

and exercise. Their use is limited to a

maximum of 12 weeks due to the risk of

serious effects on the blood supply to

the lungs and on heart valves.

apraxiaAn inability to carry out pur-

poseful movements despite normal

muscle power and coordination. Aprax-

ia is caused by damage to nerve tracts

in the cerebrum(the main mass of the

brain) that translate the idea for a move-

ment into an actual movement. Damage

to the cerebrum may be caused by a head

injury, infection,stroke, or brain tumour.

There are various forms of apraxia,

each related to damage in different

parts of the brain. A person with ideo-

motor apraxia is unable to carry out a

spoken command to make a particular

movement, but at other times can make

the same movement unconsciously. In

sensory apraxia, a person may not be

able to use an object due to loss of abil-

ity to recognize its purpose.

APUD cell tumourA growth composed

of cells that produce various hormones.

These cells, amine precursor uptake

and decarboxylation (APUD) cells, occur

in different parts of the body. Some tu-

mours of the thyroid gland, pancreas,

and lungs are APUD cell tumours, as are

a carcinoid tumour (see carcinoid syn-

drome) and phaeochromocytoma(a type

of adrenal tumour).

aqueous creamAnemollientprepara-

tion that is commonly used to treat

dry, scaly, or itchy skin in conditions

such as eczema.

aqueous humourA watery fluid that

fills the front chamber of the eye,

behind the cornea.

arachidonic acid One of the fatty acids

in the body that are essential for growth.

arachis oilPeanut oil, mostly used in

enemas, to soften faeces and make

bowel movements easier. It may also be

applied to the scalp, followed by sham-

pooing, in the treatment of cradle cap.

arachnodactylyLong, thin, spider-like

fingers and toes that sometimes occur

spontaneously but are characteristic of

Marfan’s syndrome, an inherited con-

nective tissue disease.

arachnoiditisA rare condition that is

characterized by chronic inflammation

and thickening of the arachnoid mater,

which is the middle of the 3 meninges

(the membranes that cover the brain

and spinal cord).

arachnoid materThe middle of the 3

layers of membrane (meninges) that

cover the brain.

arbovirusAny of the many viruses trans-

mitted by a member of the arthropod

group of animals, including insects,

APPETITE ARBOVIRUS

A

Colon

Ileum

APPENDIX

Appendix

Rectum

Caecum