and cancer of the
colon, cancer of; rectum,
). Vegetarian diets are low in
especially saturated fats (which may
coronary artery disease
and possibly some forms of cancer).
These diets are also likely to contain
vegetarians tend to have lower blood
pressure than people who eat meat.
vegetative state A term that is some-
used to describe a type of
. Although the
eyes may be open and occasional ran-
dom movements of the head and limbs
may occur, there are no other signs of
consciousness, and there is no respon-
siveness to stimuli. Only the basic
functions, such as breathing and heart-
beat, are maintained.
vein A vessel that returns blood towards
from the various organs and
tissues of the body. The walls of veins,
like those of arteries, consist of a
smooth inner lining, a muscular middle
layer, and a fibrous outer covering.
However, blood pressure in veins is
lower than in arteries, and the walls of
veins are thinner, less elastic, less mus-
cular, and weaker than those of arteries.
The linings of many veins contain folds,
which act as valves, ensuring that blood
flows only towards the heart. Blood is
helped on its way through the veins by
pressure on the vessel walls from the
contraction of surrounding muscles.
STRUCTURE OF A VEIN
veins, disorders of Common disorders
deep vein thrombosis (see
vena cava Either of 2 large
which all circulating (deoxygenated) blood
drains. The venae cavae (superior and
inferior) deliver blood to the right atrium
for pumping to the lungs.
VEN A CAVA
The superior vena cava starts at the top
of the chest, close to the
passes down through the
before connecting to the right atrium. It
collects blood from the upper trunk,
head, neck, and arms. The inferior vena
cava starts in the lower abdomen and
travels upwards in front of the spine,
behind the liver, and through the
before joining the right atrium.
It collects blood from the legs, pelvic
organs, liver, and kidneys,
A common procedure in
usually in the forearm, is
pierced with a needle to inject fluid or
withdraw blood. A
is used to
swell the veins, and a sterile needle is
inserted. A syringe is attached to the
needle if blood is to be taken or medica-
tion injected. For
cannula (tube) is inserted via the needle.
After the fluid has been injected or
withdrawn, the needle or cannula is
removed. The area is then covered and