HERMAPHRODITISM
HEROIN ABUSE
in which both inheritance and environ-
ment probably play a part.
A rough estimate of heritability can be
obtained from the known incidence of a
disorder in the first-degree relatives of
affected people compared with the inci-
dence of the disorder in a population
exposed to similar environmental influ-
ences. Estimates of heritability are
useful in
genetic counselling.
(See also
genetic disorders.)
hermaphroditism
A
congenital
disor-
der in which
gonads
of both sexes are
present, and the external genitalia are
not clearly male or female. True herm-
aphroditism is extremely rare and its
cause unknown. A more common con-
dition
is
pseudohermaphroditism
, in
which the gonads of only
1
sex are
present, but the ex-
INGUINAL HERNIA
ternal genitalia are
not
clearly
either
male or female.
hernia
The protru-
sion of an organ or
tissue through a weak
area in the muscle
or other tissue that
normally contains it.
The term is usually
applied to a protru-
sion of the intestine
through the abdom-
inal wall. In a
hiatus
hernia,
the stomach
protrudes through the
diaphragm and into
the chest.
Abdominal hernias
are usually due to a
congenital
weakness
in the wall of the ab-
domen. The hernias
may result from dam-
age caused by lifting
heavy objects, per-
sistent coughing, or
straining to defae-
cate, or may develop
after an operation.
There are several types of hernia, and
they are classified according to their lo-
cation in the body. The most important
are inguinal hernias, which mainly affect
men; femoral hernias, which are more
UMBILICAL HERNIA
H
common in overweight women; and
umbilical hernias, which occur in babies.
The 1st symptom of an abdominal
hernia is usually a bulge in the abdomi-
nal wall. There may also be abdominal
discomfort. Sometimes the protruding
intestine can be pushed back into place.
Severe pain occurs when the hernia
bulges out and cannot be put back;
surgery (see
hernia repair
) is usually nec-
essary. If the blood supply to a twisted,
trapped portion of intestine becomes
impaired (a strangulated hernia),
gan-
grene
of the bowel may develop. A
strangulated
hernia
requires
urgent
treatment. Umbilical hernias in babies
can usually be left untreated as they
tend to disappear naturally by age 5.
hernia repair
Surgical correction of a
hernia
.
Surgery is usually performed to
treat a hernia of the abdominal wall that
is painful or cannot be pushed back into
place. A strangulated hernia requires an
emergency operation. During surgery, the
protruding intestine is pushed back into
the abdomen and the weakened muscle
wall is strengthened. Either open or
minimally invasive surgery
may be used.
herniated disc
See
disc prolapse
.
herniorrhaphy
Surgical correction of a
hernia
.
(See
hernia repair
.)
heroin
A
narcotic drug
similar to
mor-
phine
. When used for medical purposes,
it is generally known as
diamorphine
.
Heroin is a white or brownish powder
that can be smoked, sniffed, or dis-
solved in water and injected.
As well as having an analgesic effect,
heroin produces sensations of warmth,
calmness, drowsiness, and a loss of
concern for outside events. Long-term
use of the drug causes
tolerance
and
psychological and physical dependence
(see
drug dependence; heroin abuse
).
Sudden withdrawal produces shivering,
abdominal cramps, diarrhoea, vomiting,
and restlessness.
heroin abuse
Nonmedical use of hero-
in. Heroin addiction has many adverse
effects on the user, including injection
scars,
skin
abscesses, weight
loss,
impotence, and the risk of infection
with
hepatitis B
,
hepatitis C
, and
HIV
through sharing needles. Death com-
monly occurs from accidental overdose.
280
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