adrenal hyperplasia, congenitalAn
uncommon genetic disorderin which an
enzymedefect blocks the production
of corticosteroid hormones from the
adrenal glands. Excessive amounts of
androgens(male sex hormones) are pro-
duced, which can result in abnormal
genital development in an affected fetus.
Other effects include dehydration,
weight loss, low blood pressure, and
hypoglycaemia. Hyperplasia (enlarge-
ment) of the adrenal glands occurs and
there is excessive skin pigmentation in
skin creases and around the nipples.
In severe cases, the disorder is appar-
ent soon after birth. In milder cases,
symptoms appear later, sometimes pro-
ducing premature puberty in boys and
delayed menstruation, hirsutism, and
potential infertility in girls.
Congenital adrenal hyperplasia is con-
firmed by measuring corticosteroid
hormones in blood and urine. Treat-
ment is by hormone replacement. If this
is started early, normal sexual develop-
ment and fertility usually follow.
adrenaline A hormone, also called
epinephrine, released by the adrenal
glands in response to signals from the
sympathetic autonomic nervous system.
These signals are triggered by stress,
exercise, or by an emotion such as fear.
Adrenaline increases the speed and
force of the heartbeat. It widens the air-
ways to improve breathing and narrows
blood vessels in the skin and intestine
so that an increased flow of blood
reaches the muscles.
Synthetic adrenaline is sometimes
given by injection as an emergency
treatment for cardiac arrestor anaphy-
lactic shock. Adrenaline eye drops may
be used to treat glaucoma, but regular
use can cause a burning pain in the eye.
adrenal tumoursCancerous or non-
cancerous tumours in the adrenal
glands, usually causing excess secretion
of hormones. Adrenal tumours are rare.
Tumours of the adrenal cortex may
secrete aldosterone, causing primary
aldosteronism, or hydrocortisone, caus-
ing Cushing’s syndrome. Tumours of
the medullamay cause excess secretion
of adrenalineand noradrenaline. Two
types of tumour affect the medulla:phaeochromocytoma and neuroblastoma,
which affects children. These tumours
cause intermittent hypertension and
sweating attacks. Surgical removal of a
tumour usually cures these conditions.
adrenocorticotrophic hormoneSee
ACTH.
adrenogenital syndromeSee adrenal
hyperplasia,congenital.
aerobicRequiring oxygen to live, func-
tion, and grow. Humans and many
other forms of life are dependent on
oxygen for “burning” foods to produce
energy (see metabolism). In contrast,
many bacteria thrive without oxygen
and are described as anaerobic.
aerobicsExercises, such as swimming
and cycling, that allow muscles to work
at a steady rate with a constant, ade-
quate supply of oxygen-carrying blood,
and that can therefore be sustained for
long periods. Oxygen is used to release
energy from the body’s stores. To fuel
aerobic exercise, the muscles use fatty
acid, burning it completelyto produce
energy, carbon dioxide, and water.
When performed regularly, aerobic
exercises improve stamina and endur-
ance. They encourage the growth of
capillaries, improving blood supply to
the cells. Aerobic exercises also improve
body cells’ capacity to use oxygen and
increase the amount of oxygen the body
can use in a given time. The condition
of the heart also improves. (See also
exercise; fitness.)
aerodontalgiaSudden pain in a tooth
brought on by a change in surrounding
air pressure. Flying at a high altitude in
a lowered atmospheric pressure can
cause a pocket of air in the dental pulp
to expand and irritate the nerve in the
root. Aerodontalgia is more likely if
there are improperly fitting fillings or
poorly filled root canals.
aerophagyExcessive swallowing of air,
which may occur during rapid eating or
drinking or be caused by anxiety.
aetiologyThe cause of a disease or the
study of the various factors involved in
causing a disease.
affectA term used to describe a per-
son’s mood. The 2 extremes of affect are
elation and depression. A person who
experiences extreme moods or changesADRENAL HYPERPLASIA, CONGENITAL AFFECTA