Those that cause
divergence have a negative number and
are used to correct shortsightedness
A highly toxic group of chemi-
cals. They are contaminants of some
defoliant weedkillers (see
used to treat allergic disorders such as
. It is also
used for the relief of temporary sleep
tain the drug. It can cause drowsiness,
dry mouth and blurred vision.
related to the opioid
lessens the contractions of the muscles
in the intestinal walls, reducing the fre-
quency of bowel movements.
A bacterial infection that
causes a sore throat, fever, and some-
times serious or fatal complications. It is
During infection, the bacterium may
multiply in the throat or skin. In the
throat, bacterial multiplication gives
rise to a membrane that may cover the
tonsils and spread up over the palate or
down to the larynx and trachea, causing
breathing difficulties. Other symptoms
are enlarged lymph nodes in the neck,
increased heart rate, and fever. Some-
times, infection is confined to the skin.
Life-threatening symptoms develop only
in nonimmune people and are caused
by a toxin released by the bacterium. A
victim may collapse and die within a
day of developing throat symptoms.
More often the person is recovering from
sis of the throat or limbs develops.
Diphtheria is treated with antibiotics.
An antitoxin is also given if diphtheria
affects the throat. If severe breathing
difficulties develop, a
be needed. Mass immunization has made
diphtheria rare in developed countries,
affecting both sides
of the body (both legs and, to a lesser
extent, both arms).
diplopia The medical
dipsomania A form of
in which periods of excessive
drinking and craving for drink alternate
with periods of relative sobriety.
A drug that reduces the
stickiness of platelets in the
thereby helps to prevent the formation
of abnormal blood clots within arteries.
Dipyridamole is used with
to prevent the formation of
may also be given to people who have
had a recent
coronary artery bypass
Dipyridamole may also reduce the fre-
transient ischaemic attacks.
Possible adverse may include head-
ache, flushing, and dizziness.
A physical or mental loss or
impairment that is measurable. (See
A visible emission of fluid
from an orifice or a break in the skin. A
discharge may be a normal occurrence,
as in some types of
but it could also be due to an infection
A flat, circular,
plate-like structure containing
that lines the joints between adjacent
(bones) in the
. Each inter-
vertebral disc is composed of a fibrous
outer layer and a soft gelatinous core. It
acts as a shock absorber to cushion the
vertebrae during movements of the spine.
With increasing age, intervertebral discs
become less supple and more suscepti-
ble to damage from injury.