15.
The coronary arteries supply "nutritive" blood to the heart walls. The coronary
arteries arise from the base of the aortic arch and are spread over the surface of
the heart. This blood is collected by the cardiac veins, which empty into the right
atrium of the heart. If a coronary artery becomes closed, the receiving area of the
16.
The pericardium is a special serous sac surrounding the heart and reducing the
frictional forces upon its moving surfaces. (para 9-7d)
17.
The human cardiovascular system is closed because at no place is whole blood
ever outside the system. It is two-cycle because the blood passes through the
heart twice with each complete circuit of the body. In the pulmonary cycle, the
blood passes from the right heart, through the lungs, and to the left heart. In the
systemic cycle, the blood passes from the left heart, through the body in general,
18.
In the case of collateral circulation, if one blood vessel to an area is damaged,
then another blood vessel will continue the supply. However, when an end artery
19.
PULMONARY CYCLE: The pulmonary cycle begins in the right ventricle.
Contraction of the wall of the right ventricle forces the tricuspid valve to close.
This keeps blood from flowing back into the right atrium. The pressure forces
blood past the pulmonary semilunar valve into the pulmonary trunk. Upon
relaxation of the right ventricle, back pressure of the blood in the pulmonary trunk
closes the pulmonary semilunar valve. The blood then passes into the lungs
through the pulmonary arterial system. Gases are exchanged between the alveoli
of the lungs and the blood in the capillaries next to the alveoli. The oxygenated
blood is collected by the pulmonary veins and carried to the left atrium of the heart.
20.
SYSTEMIC CYCLE: Oxygenated blood is moved from the left atrium into the left
ventricle. Contraction of the wall of the left ventricle closes the mitral valve, which
prevents blood from returning to the left atrium. The pressure forces blood past
the aortic semilunar valve into the aortic arch. Upon relaxation of the left
ventricular wall, back pressure of the blood in the aortic arch closes the aortic
semilunar valve. The blood then passes through the various arteries to the tissues
of the body. Materials are exchanged between the blood and cells of the body in
the capillary beds. The blood returns to the right atrium of the heart in vessels
21.
The head is supplied by the carotid arteries. The neck and upper members are
supplied by the subclavian arteries. The aortic arch continues as a large single
vessel known as the aorta. At the lower end of the trunk, the aorta divides into the
right and left iliac arteries, supplying the pelvic region and lower members.
MD0006
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