Brain damage is likely if the brain is
starved of blood, and therefore oxygen,
for more than three to four minutes.
First, mouth-to-mouth resuscitation
is given in order
to restart the casualty’s breathing. If this
step fails, repeated chest compressions,
using the heel of the hand, are applied
to the lower part of the breastbone (see
external cardiac massage
measures are used alternately to restore
blood circulation to the brain.
fetal heart monitoring
A term that means “ pertaining to the
heart and blood vessels” .
Disorders of the heart (see
ders box), blood vessels, and blood
veins, disorders of
The branch of surgery that is con-
vessels. Cardiovascular surgery can be
divided into two main areas.
One area, sometimes called cardio-
thoracic surgery, includes operations to
prevent or repair damage to the heart
itself and to the major blood vessels
w ithin the chest cavity. Cardiothoracic
surgery is used, for example, to help
treat damage due to congenital heart
heart disease, congenital
The second area, w hich is known as
vascular surgery, is concerned with the
treatment of blood vessels elsewhere in
the body, such as in the legs. (See also
heart valve surgery
coronary artery bypass
An alternative name for
A general term for inflammation of any
part of the heart or its linings. There
are three types.
tion of the heart muscle)
caused by a viral infection.
(inflammation of the internal lining of
the heart) is usually due to a bacterial
the outer covering of the heart) is usu-
ally the result of a viral or bacterial
infection but may be associated with a
(heart attack) or an
autoimmune disorder, such as systemic
The gradual erosion of enamel
hard covering of a tooth) and dentine
(the softer substance that lies beneath
the enamel). This condition is more
commonly known as tooth decay.
of dental caries is
a sticky substance consisting of
food deposits, saliva by-products, and
bacteria that collects on the surface of
teeth. The breakdown of food deposits
by bacteria creates acid that eats into
the enamel to form cavities. Left un-
checked, decay spreads to the dentine,
and as the cavity enlarges, bacteria may
invade and destroy the pulp tissue at
the core of the tooth.
grinding surfaces of the back teeth and
on areas around the gum line. In the
early stages, dental caries does not usu-
decay causes toothache (see
however, w hich may be aggravated by
eating very sweet, hot, or cold food.
Sometimes advanced decay can also
cause halitosis (bad breath).
Treatment consists of drilling away the
area of decay and filling the cavity (see
). In advanced decay, it may
be necessary to remove the infected
pulp and replace it with a filling (see
or to extract the
The risk of dental caries occurring is
reduced by cutting down on sugar con-
sumption, practising good
and visiting the dentist regularly. Water
toothpaste also helps to prevent caries.
Carminatives are used
in the treatment of
CAUSES OF CARIES (TOOTH DECAY)
The primary cause of tooth decay is
a sticky substance that
forms on the teeth. Plaque consists of
food remains, saliva by-products, and
the bacteria that live in the mouth. The
bacteria feed mainly on the fermentable
carbohydrates (simple sugars and
starches) in food, and, in breaking them
down, create an acid that gradually
destroys enamel, forming a cavity. If the
process is not checked, the dentine is
eroded next, enlarging the cavity and
enabling the bacteria to invade the
pulp at the centre of the tooth.
Micrograph of dental caries
The surface enamel of this decaying molar tooth
is being broken down.
E n a m e l
in the break-
D e n t i n e
to the dentine.
P u lp c a v it y
the bacteria to
pulp at the
If untreated, the
infected pulp will
die and the tooth
will be destroyed.