mechanisms. Chapter 8 addresses the ultimate
purpose of the cardiovascular system, that
is, the exchange of nutrients, gases, and
fluid between the blood and tissues. Finally,
Chapter 9 integrates concepts described in
earlier chapters by examining how the cardio-
vascular system responds to altered demands
and disease states.
Large organisms require a circulatory
system so that metabolic substrates
and by-products of cellular metabolism
can be efficiently exchanged between
cells and the outside environment, as
well as transported to distant sites
within the body.
Venous blood returns to the right
side of the heart, which pumps the
blood into the pulmonary circulation
where oxygen and carbon dioxide are
exchanged with the gases found within
the lung alveoli. Oxygenated blood
from the lungs enters the left side
of the heart, which pumps the blood
at high pressure into the aorta for
distribution to various organs via large
distributing arteries. Small capillaries
within the organs serve as the primary
site of nutrient exchange.
Blood flow within organs is determined
primarily by the arterial pressure and
by changes in the diameters of blood
vessels within the organs brought
about by contraction or relaxation of
smooth muscle within the walls of the
blood vessels.
Most major organ systems are in parallel
with each other so that blood flow in
one organ has relatively little influence
on blood flow in another organ.
Negative feedback mechanisms such as
the baroreceptor reflex, acting through
autonomic nerves and circulating
hormones, help to maintain normal
arterial pressure.
For each question, choose the one best answer:
The cardiovascular system
a. Aids in the transfer of heat energy
from organs deep within the body to
the outside environment.
b. Comprises pulmonary and systemic
circulations that are in parallel with
each other.
c. Transports carbon dioxide from the
lungs to tissues within organs.
d. Transports oxygen from individual
cells to the lungs.
Which of the following statements con-
cerning the heart is true?
a. Cardiac output is the product of ven-
tricular stroke volume and heart rate.
b. The right and left ventricles are in
c. The right ventricle generates higher
pressures than the left ventricle
during contraction.
d. The right ventricle receives blood
from the pulmonary veins.
A patient complains of becoming “light
headed” when he is standing upright.
Blood pressure measurements reveal a
significant fall in arterial pressure upon
standing. Which of the following is a
likely explanation of this patient’s
a. Excessive activation of baroreceptor
negative feedback mechanisms
b. Excessive fluid retention by the
c. Increased heart rate
d. Reduced cardiac output
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