VEGETATIVE STATE
VENEPUNCTURE
V
diverticular disease
and cancer of the
intestine (see
colon, cancer of; rectum,
cancer of
). Vegetarian diets are low in
fats,
especially saturated fats (which may
contribute to
coronary artery disease
and possibly some forms of cancer).
These diets are also likely to contain
less
sodium
and more
potassium
, and
vegetarians tend to have lower blood
pressure than people who eat meat.
vegetative state A term that is some-
times
used to describe a type of
indefinite deep
coma
. 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
the
heart
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.
(See also
circulatory system
.)
STRUCTURE OF A VEIN
veins, disorders of Common disorders
affecting
veins
include
varicose veins
,
deep vein thrombosis (see
thrombosis,
deep
vein), and
thrombophlebitis.
vena cava Either of 2 large
veins
into
which all circulating (deoxygenated) blood
drains. The venae cavae (superior and
inferior) deliver blood to the right atrium
of the
heart
for pumping to the lungs.
VEN A CAVA
Carotid artery
Jugular vein
Subclavian
artery
Superior
vena cava
Inferior
vena cava
Subclavian
vein
Heart
Aorta
The superior vena cava starts at the top
of the chest, close to the
sternum
, and
passes down through the
pericardium
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
dia-
phragm
before joining the right atrium.
It collects blood from the legs, pelvic
organs, liver, and kidneys,
venepuncture
A common procedure in
which a
vein,
usually in the forearm, is
pierced with a needle to inject fluid or
withdraw blood. A
toumicpiet
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
intravenous infusion,
a
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
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