Understanding the concepts presented in this chapter will enable the student to:
Describe the cardiac and vascular changes that occur during exercise, the
mechanisms responsible for those changes, and factors that can alter the
Describe how cardiovascular function is altered during pregnancy.
Describe the conditions that can lead to hypotension and the compensatory
mechanisms that are activated to restore arterial pressure.
Explain how positive feedback mechanisms can lead to irreversible shock and
death following severe hemorrhage.
Describe several different causes of hypertension and how it is treated.
Define systolic and diastolic ventricular failure and describe how these two
types of failure alter cardiac and vascular function at rest and during physical
Describe the compensatory mechanisms that operate during heart failure.
Describe how heart valve stenosis and regurgitation affect cardiac function.
Previous chapters emphasized physiologic con-
cepts concerning cardiac and vascular function
at the cellular and organ level. In addition, they
examined mechanisms, such as baroreceptors
and circulating hormones, that regulate over-
all cardiovascular function. This chapter inte-
grates all the components of the cardiovascular
system and shows how they work together to
maintain normal perfusion of organs under
conditions of increased organ demand for
blood flow (e.g., during exercise and preg-
nancy) or during abnormal stressful condi-
tions such as hemorrhage. This chapter also
examines changes that occur in cardiovascular
function during pathologic conditions such as
hypertension, heart failure, and valve disease.
The cardiovascular system must be able to
respond to a wide range of demands placed
on it by the body. Previous chapters focused
on cardiovascular function in normal resting
states; however, physical activity is (or should
be!) a normal, daily activity of humans. Physi-
cal movement is associated with increases in
the metabolic activity of contracting muscles.
This increased metabolic activity is largely oxi-
dative; therefore, the cardiovascular system
needs to increase blood flow and oxygen deliv-
ery to the contracting muscles.
The cardiovascular responses to physical
activity are summarized in Table 9-1. If large
muscle groups are involved in the physical