ANAL STENOSIS
ANDROGEN DRUGS
of a weak opioid analgesic, such as
codeine,
with a nonopioid analgesic
relieve more severe pain. Potent opioids
such as
morphine
are used only when
other preparations would be ineffective
because they can produce
tolerance
and
drug dependence.
Adverse effects are uncommon with
paracetamol. Aspirin and NSAIDs may
irritate the stomach lining and cause
nausea, abdominal pain, and, rarely, a
peptic ulcer
. Nausea, drowsiness, con-
stipation, and breathing difficulties may
occur with opioid analgesics.
anal stenosis
A tightness of the anus,
sometimes referred to as anal stricture.
Anal stenosis prevents the normal pas-
sage of faeces, causing constipation and
pain during defaecation. The condition
may be present from birth, or may be
caused by a number of conditions in
which scarring has occurred, such as
anal fissure
,
colitis
, or cancer of the anus.
Anal stenosis sometimes occurs after
surgery on the anus (for example, to
treat
haemorrhoids
). The condition is
treated by
anal dilatation
.
anal stricture
See
an a stenosis.
anal tag
A type of
skin tag.
analysis, chemical
Determination of
the identity of a substance or of the
individual chemical constituents of a
mixture. Analysis may be qualitative, as
in determining whether a particular
substance is present, or it may be quan-
titative, that is, measuring the amount
or concentration of one or more consti-
tuents. (See also
assay
.)
analysis, psychological
See
psycho-
anaysis.
anaphylactic shock
A rare, life-threat-
ening allergic reaction that occurs in
people with an extreme sensitivity to a
particular substance (allergen), often in-
sect venom, a food item, or a drug (see
allergy
). When the allergen enters the
bloodstream, massive amounts of
hista-
mine
and other chemicals are released,
causing sudden, severe lowering of
blood pressure and constriction of the
airways. Other symptoms may include
abdominal pain, diarrhoea, swelling of
the tongue and throat, and itchy rash.
Anaphylactic shock requires emerg-
ency medical treatment. An injection of
adrenaline
may be life-saving.
Antihis-
tamine drugs
and
corticosteroid drugs
may also be given.
anastomosis
A
natural
or
artificial
communication between 2 blood ves-
sels or tubular cavities that may or may
not normally be joined. Natural anasto-
moses usually occur when small
arteries
are attached directly to
veins
without
passing through capillaries. They occur
in the skin and are used to help control
temperature regulation. Surgical anas-
tomoses are used to create a bypass
around a blockage in an artery or in the
intestine. They are also used to rejoin
cut ends of the bowel or blood vessels.
(See also
bypass surgery.
)
anatomy
The structure of the body of
any living thing, and its scientific study.
Human anatomy, together with
physiol-
ogy
(the study of the functioning of the
body), forms the foundation of medical
science. Anatomy is subdivided into
many branches. These include compara-
tive anatomy (the study of the differences
between human and animal bodies),
surgical anatomy (the practical know-
ledge required by surgeons),
embryology
(the study of structural changes that
occur during the development of the
embryo and fetus), systematic anatomy
(the study of the structure of particular
body systems), and
cytology
and
histol-
ogy
(the microscopic study of cells and
tissues respectively).
ancylostomiasis
See
hookworm infes-
tation
.
androgen drugs
Natural or synthetic
androgen horm ones
used as drugs; one
of the most important is
testosterone
.
These drugs are used in the treatment
of male
hypogonadism
(underactivity of
the testes) to stimulate the development
of sexual characteristics.
Androgen drugs are occasionally used
to treat certain types of
breast cancer
.
They have been widely used by sports-
men wishing to increase muscle bulk
and strength, a practice that is danger-
ous to health (see
steroids
,
anabolic
).
Adverse effects include fluid retention,
weight gain, increased blood cholesterol,
and, rarely, liver damage. When taken by
women, the drugs can cause male char-
acteristics, such as facial hair, to develop.
A
33
previous page 31 BMA Illustrated Medical Dictionary read online next page 33 BMA Illustrated Medical Dictionary read online Home Toggle text on/off