abbreviation for histamine
agonists, a group of
cimetidine; ranitidine; famotidine.)
The process of becoming
accustomed to an experience. In general,
the more a person is exposed to a stim-
ulus, the less he or she is affected by it.
People can become habituated to certain
drugs and develop a reduced response
to their effects (see
A compound that contains iron
and which combines with globin to
A prefix indicating
A rare type of brain
tumour consisting of blood-vessel cells.
Haemangioblastomas develop slowly as
cysts, often in the cerebellum, and are
mostly noncancerous. Symptoms include
and, if the
tumour is in the cerebellum,
can be removed surgically.
A birthmark caused by
abnormal distribution of blood vessels.
Types of haemangioma include
. They generally disappear without
leaving a scar by 5-7 years.
Haemangiomas do not usually require
treatment. However, a haemangioma
that bleeds persistently or that looks
unsightly may need to be removed, by
Bleeding into a
causing the capsule that encloses the
joint to swell, and resulting in pain and
stiffness. Haemarthrosis is usually the
result of severe injury to a joint. Less
common causes are
, and overuse of
may reduce swelling and
pain. Fluid may be withdrawn for pain
relief and for diagnosis. Haemophiliacs
to promote blood
clotting. Resting the joint in an elevated
position can prevent further bleeding.
Repeated haemarthrosis may damage
joint surfaces, causing
The medical term for
The study of
its formation, as well as the investiga-
tion and treatment of disorders that
affect the blood and the
A localized collection of
(usually clotted) that is caused by
bleeding from a ruptured blood vessel.
Haematomas can occur almost any-
where in the body and vary from a
minor to a potentially fatal condition.
Less serious types of haematoma in-
clude haematomas under the nails or in
the tissues of the outer ear (
). Most haematomas disappear with-
out treatment in a few days, but if they
are painful they may be drained. More
serious types include extradural and
subdural haematomas, which press on
the brain (see
The medical term
Blood in the
may or may not be visible to the naked
eye. In small amounts, it may give the
urine a smoky appearance.
Urinary tract infection
is a common cause;
may be a
cause in men.
, stones (see
may cause haematuria.
may also cause the condition.
Blood that is not visible to the naked
eye may be detected by a dipstick
or microscopic examination.
, or intra-
can help determine
the cause. If bladder disease is suspect-
An inherited dis-
ease in which too much dietary iron is
Excess iron gradually ac-
cumulates in the liver, pancreas, heart,
testes, and other organs. Men are more
frequently affected because women reg-
ularly lose iron in menstrual blood.