LEARNING OBJECTIVES
VASCULAR FUNCTION
Understanding the concepts presented in this chapter will enable the student to:
Name the different types of vessels constituting the vascular network of the
body and describe the general function of each.
Describe how changes in cardiac output, systemic vascular resistance, and
central venous pressure affect mean arterial pressure.
Describe the factors that determine arterial pulse pressure.
Describe in quantitative terms how changes in vessel radius, vessel length,
blood viscosity, and perfusion pressure affect blood flow.
Explain how turbulent flow alters the relationship between pressure and flow.
Calculate total resistance from series or parallel resistance networks.
Explain why the pressure drop across small arteries and arterioles is much
greater than the pressure drop across other vessel types.
8.
Define vascular tone and list factors that alter vascular tone.
9.
Explain how each of the following affects central venous pressure: blood
volume, venous compliance, gravity, respiration, and muscle contraction.
10. Using cardiac and systemic function curves, explain how changes in blood
volume, venous compliance, vascular resistance, and cardiac performance
influence the equilibrium between right atrial pressure and cardiac output.
INTRODUCTION
The vascular system serves two basic func-
tions: distribution and exchange. Distribution
includes transporting blood to and away from
organs. Exchange involves the movement of
gases, nutrients, and fluid between the blood
and tissues. This chapter focuses on vascu-
lar anatomy and the general hemodynamic
principles involved in the regulation of blood
pressure and the distribution of blood flow
in the body. Chapters 6 and 7 describe these
physiologic
control
mechanisms
in
more
detail. The exchange function is described in
Chapter 8.
ANATOMY AND FUNCTION
Vascular Network
The left ventricle ejects blood into the aorta,
which then distributes the blood flow through-
out the body using a network of arterial ves-
sels, which branch into successively smaller
vessels until they reach the smallest vascular
unit, capillaries, within organs and tissues.
Capillaries then converge into successively
larger vessels (veins), which return the blood
to the heart. These vessels are illustrated in
Figure 5.1. Table 5-1 summarizes the relative
sizes and functions of different blood vessels.
93
CHAPTER
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