and there may be evidence of failure to
thrive (restricted growth). In addition,
heart abnormalities and
(abnormally low levels of calcium in
the blood) may occur.
Transplants of thymus tissue, or
may be successful in
treating the immunodeficiency.
The process by w hich food is broken
down into smaller components that can
be transported and used by the body.
The group of organs responsible for
The digestive system consists
of the digestive tract (also known as
the alimentary tract or canal) and vari-
ous associated organs.
make up the digestive tract. The intes-
Associated organs, such as the
secrete digestive juices that help break
down food as it goes through the tract.
Food and the products of digestion are
moved from the throat to the rectum
(waves of muscular con-
tractions of the intestinal wall).
Food is broken down into simpler
substances before being absorbed into
the bloodstream. Physical breakdown is
performed by the teeth, w hich cut and
chew, and the stomach, w hich churns
the food. Chemical breakdown of food
is performed by the action of
(biological catalysts), acids, and salts.
are broken down
are broken down into
In the mouth, saliva lubricates food
and contains enzymes that begin to
break down carbohydrates. The tongue
moulds food into balls (called boli) for
easy swallowing. The food then passes
into the pharynx, from where it is
pushed into the oesophagus and is then
squeezed down into the stomach. Once
in the stomach, the food is mixed with
hydrochloric acid and pepsin. These
substances, produced by the stomach
lining, help to break down proteins.
W hen the food has been converted to a
sem i-liquid consistency, it passes into
the duodenum, where bile salts and
acids (produced by the liver) help to
break down the fats it contains. Diges-
tive juices released by the pancreas into
the duodenum contain enzymes that
further break down food.
Breakdown concludes in the small
intestine, carried out by enzymes that
are produced by glands in the intestinal
lining. Nutrients are absorbed in the
small intestine through tiny projections
from the intestinal wall, called villi. The
food residue enters the large intestine,
where much of the water it contains is
absorbed by the lining of the colon.
Undigested matter is expelled via the
rectum and anus as
A division, such as a
located at the end of a limb.
A group of drugs that are extracted
from plants belonging to the foxglove
family. They are used to treat heart con-
ditions, most commonly
(irregular, rapid beating of the upper
chambers of the heart). Those most fre-
quently used are
digital subtraction angiography
that is used
and certain types of
The most widely used of the
Digoxin is used in the treatment
and certain types of
(irregular heartbeat), such
Blood tests are sometimes needed to
ensure the correct digoxin dose, espec-
ially in patients with kidney disease. An
loss of appetite, nausea and vomiting,
and visual disturbances. Digoxin occa-
sionally disrupts the normal heartbeat,
Di Guglielmo’s disease
A form of acute myeloblastic leukaemia
) characterized by
excessive numbers of red blood cells in
the bone marrow and bloodstream.
A type of opioid
killer). Side effects of dihydrocodeine
include nausea and vomiting.
A condition in w hich a body cavity,
stretched due to normal physiological
processes (such as
) or because
of the effects of disease.
The term “dilatation” also refers to
medical procedures for achieving such
enlargement, as in dilatation and curet-
dilatation and curettage
D and C
A term that is sometimes used as an
An instrument used for stretching and
enlarging a narrowed body cavity, pas-
sage, or opening, for example to enable
an investigative procedure or surgery.
calcium channel blocker
drug that is
used in the treatment of
(high blood pressure) and
(chest pain due to impaired blood
supply to the heart muscle). Side effects
of diltiazem may include headaches,
loss of appetite, nausea, constipation,
and swollen ankles.
A silicone-based substance, also known
as simeticone, that is used in
and as an antifoaming agent in
A unit of the power of
“strength”) of a lens; the greater the
power, the stronger the lens. Lenses
that cause parallel light rays to con-
verge have a positive dioptric number
and are used to correct longsighted-
cause light rays to diverge have a nega-
tive number and are used to correct
The name of a highly toxic group of
chemicals. Dioxins are contaminants of
some defoliant weedkillers (see