18. In the case of collateral circulation, if one blood vessel to an area is
damaged, then
. However, when an end artery
is damaged, the receiving area will usually
.
19.
PULMONARY CYCLE:
In which chamber of the heart does the pulmonary cycle begin?
Contraction of the wall of the right ventricle forces the
valve to
close. This keeps blood from flowing back into the
. The pressure forces
blood past the
valve into the
. Upon relaxation of the right
ventricle, back pressure of the blood in the pulmonary trunk closes the
valve.
The blood then passes into the
through the pulmonary arterial system. Gases are
exchanged between the
of the lungs and the blood in the
next to the
alveoli. The oxygenated blood is collected by the
and carried to the
of the heart. This completes the pulmonary cycle.
20.
SYSTEMIC CYCLE:
Oxygenated blood is moved from the left atrium into the
.
Contraction of the wall of the left ventricle closes the
valve, which prevents
blood from returning to the
. The pressure forces blood past the
valve into the
. Upon relaxation of the left ventricular wall,
back pressure of the blood in the aortic arch closes the
valve. The blood then
passes through the various
to the
. Materials are exchanged
between the blood and cells of the body in the
. The blood returns to the
of the heart in vessels called
.
21. The head is supplied by the
arteries. The neck and upper
members are supplied by the
arteries. The aortic arch continues as a
large single vessel known as the
. At the lower end of the trunk, the aorta
divides into the right and left
arteries, supplying the pelvic region and lower
members.
22. Running parallel to the arteries is the system of
veins. Immediately
beneath the skin is a network of
veins. These veins collect and then join the
deep veins in the
(armpits) and the
(groin). Collecting the blood from
the head, neck, and upper members is the superior
. Collecting the blood
from the rest of the body is the
. Thus, the final major veins,
emptying the returned blood into the right atrium of the heart, are the
.
Except the veins from the head, veins are generally supplied with
s to assist
in making blood flow toward the heart. Carrying absorbed substances from the gut to
the liver is the
. After being specially treated and conditioned, this
blood is returned to the general circulation by the
veins.
MD0006
9-21