APPETITE
ARBOVIRUS
A
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).
APPENDIX
appetite
A 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
hunger
to
ensure that the right amount of a wide
range of foods is eaten to stay healthy.
(See also
appetite, loss
of.)
appetite, loss of
Loss 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 stimulants
Various tonics and
remedies
traditionally
prescribed
to
stimulate the appetite. None are proven
to be effective. Some drugs such as
cor-
ticosteroids
may stimulate the appetite
when used to treat unrelated disorders.
appetite suppressants
A 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.
apraxia
An 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 tumour
A 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
phaeochrom ocytom a
(a type
of adrenal tumour).
aqueous cream
An
emollient
prepara-
tion that is commonly used to treat
dry, scaly, or itchy skin in conditions
such as
eczema.
aqueous humour
A 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 oil
Peanut oil, mostly used in
enem as
, 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
.
arachnodactyly
Long, thin, spider-like
fingers and toes that sometimes occur
spontaneously but are characteristic of
Marfan's syndrome,
an inherited con-
nective tissue disease.
arachnoiditis
A 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 mater
The middle of the 3
layers of membrane (
m eninges
) that
cover the
brain.
arbovirus
Any of the many viruses trans-
mitted by a member of the arthropod
group of animals, including insects,
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