emergency treatment of epilepsy, and to
treat alcohol withdrawal symptoms. It
may also be given intravenously to pro-
duce sedation in people undergoing
certain procedures, such as endoscopy.
Diazepam may cause drowsiness, diz-
ziness, and confusion; therefore driving
and hazardous work should be avoided.
Diazepam can be habit-forming.
DICSee disseminated intravascular co-
agulation.
diclofenacA nonsteroidal anti-inflam-
matory drug(NSAID) used to relieve
pain and stiffness in arthritisand to
hasten recovery following injury. Side
effects may include nausea, abdominal
pain, and peptic ulcer.
dietSee nutrition.
diet and diseaseSeveral diseases are
linked with diet. Diseases due to a defi-
ciency are rare in developed countries,
but many disorders are due partly to
overconsumption of certain foods. A
diet high in fats may contribute to
atherosclerosis and heart disease. A
high-fat diet has also been linked with
cancer of the bowel (see colon, cancer
of) and breast cancer. Obesityincreases
the risk of many other disorders, includ-
ing diabetes mellitusand stroke.
Overconsumption of alcoholcan lead
to various alcohol-related disorders. A
high salt intake predisposes a person
towards hypertension. Some compon-
ents of the diet protect against disease.
For example, fibre protects against di-
verticular disease, chronic constipation,
and haemorrhoids.
Many people’s diets contain too few
natural vitamins. Pregnant women need
high intakes of folic acidto reduce the
risk of neural tube defects.
Although many illnesses are commonly
ascribed to food allergy, it is only rarely
that a definite link is proved. (See also
nutritional disorders).
dieteticsThe application of nutritional
science to maintain or restore health. It
involves a knowledge of the composi-
tion of foods, the effects of cooking and
processing, and dietary requirements,
as well as psychological aspects, such as
eating habits (see nutrition).
diethylstilbestrolA synthetic form of
the female sex hormone oestrogen,
occasionally used to treat prostate can-
cer (see prostate, cancer of) and, in
postmenopausal women only, breast
cancer. Common side effects include
nausea, oedema, and breast enlarge-
ment (gynaecomastia) in men.
differentiationThe process by which
the cells of the early embryodiversify to
form the distinct tissues and organs. It
also means the degree to which the
microscopic appearance of cancerous
tissue resembles normal tissue.
diffusionThe spread of a substance in
a fluid from an area of high concentra-
tion to one of lower concentration.
diflunisalA nonsteroidal anti-inflamma-
tory drug(NSAID) used to relieve joint
pain and stiffness in types of arthritis.
The drug is also given for back pain,
sprains, and strains. Side effects include
nausea, diarrhoea, and a rash.
digestionThe process by which food is
broken down into smaller components
that can be transported and used by the
body. (See also digestive system).
digestive systemThe group of organs
responsible for digestion. It consists of
the digestive tract (also known as the
alimentary tract or canal) and various
associated organs. The digestive tract
consists of the mouth, pharynx, oesoph-
agus, stomach, intestines, and the anus.
The intestines are the small intestine
(comprising the duodenum, jejunum,
and ileum) and the large intestine (com-
prising the caecum, colon, and rectum).
The associated organs, such as the sali-
vary glands, liver, and pancreas, secrete
digestive juices that break down food as
it goes through the tract.
Food and the products of digestion
are moved from the throat to the rec-
tum by peristalsis(waves of muscular
contractions of the intestinal wall).
Food is broken down into simpler sub-
stances before being absorbed into the
bloodstream.Physical breakdown is per-
formed by the teeth, which cut and chew,
and the stomach, which churns the
food. The chemical breakdown of food
is performed by the action of enzymes,
acids, and salts.
Carbohydratesare broken down into
simple sugars. Proteinsare broken down
into polypeptides, peptides, and aminoDIC DIGESTIVE SYSTEM
D