11.
The three layers in the walls of the heart chambers are the
m, the
m, and the
m. The inner layer is a smooth e
. The
middle layer is made up of cardiac
tissue. The outer layer is another
e
.
12. THIN OR THICK? The atrial walls are relatively
. The right
ventricular wall is much
er than the atrial walls. The left ventricular wall is
three to five times
er than the right ventricular wall.
13.
The valve between the atrium and ventricle of each side is the
( ) valve. The right A-V valve is known as the
valve. The left A-V
valve is known as the
valve. The fibrous cords attached to the underside of
the A-V valves are called
. They are attached to the inner walls of the
ventricles by
muscles. The valve at the base of the pulmonary trunk and the
valve at the base of the aortic arch are both
valves, each with
cusps. They are often called the
valve and the
valve.
14. Extrinsic nervous control of the heart is exerted by nerves of the
nervous system. Speeding the heart up are the
cardiac nerves. Slowing the
heart down is the v
p
nerve. Intrinsic "nervous" control is built within the
. It consists of the s
( ) node, the a
( ) nodes,
and the s
b
. For humoral control, there appears to be
which have varying effects upon the functioning of the heart.
15. The coronary arteries supply "
" blood to the heart walls. The
coronary arteries arise from the base of the
and are spread over the surface
of the heart. This blood is collected by the
veins, which empty into the right
of the heart. If a coronary artery becomes closed, the receiving area of the
heart will probably
.
16. The pericardium is a special serous sac surrounding the ______________
and reducing the
l forces upon its moving surfaces.
17. The human cardiovascular system is closed because at no place is whole
blood ever
. It is two-cycle because the blood passes
through the heart twice with each complete
. In the pulmonary cycle, the
blood passes from the
heart, through the
, and to the
heart. In the systemic cycle, the blood passes from the
heart, through the
, and returns to the
heart.
MD0006
9-20