Download CHAPTER 21: CARDIOVASCULAR SYSTEM: PERIPHERAL

CHAPTER 21: CARDIOVASCULAR SYSTEM: PERIPHERAL
CIRCULATION AND REGULATION
Topics Related to Peripheral Circulation and Regulation
The heart is the pump that provides the major force causing blood to circulate, and the blood vessels are the pipes that
carry blood to tissues of the body and back to the heart. Additionally, blood vessels participate in the regulation of
blood pressure and help to direct blood flow to tissues that are most active.
Clinical topics will stimulate interest in the physiology of peripheral circulation. The Clinical Focus: Hypertension,
p. 751, will provide basic information of this subject. Encourage student investigation of the causes and treatments for
essential and chronic hypertension. As they learn about the physiology of systemic circulation, students will begin to
realize the number of factors that can contribute to hypertension and why it can be difficult to “cure”.
There will be lots of interest in exercise and cardiovascular health. Use Clinical Focus: Blood Flow Through
Tissues During Exercise, p. 754, as a starting point and have students determine what forms of exercise are
associated with cardiovascular fitness.
The Clinical Focus: Shock, pages 760-761, can be used to develop a class discussion around this important
phenomenon. Have students research different first aid procedures that relate to the different kinds of shock.
Themes From Chapter 21
Structure and Function
General Features of Blood Vessel Structure
Be sure to cover structure and function of capillaries adequately so students can understand gas exchange,
nutrient absorption, and functions in the urinary system.
The concepts of vasoconstriction and vasodilation are very important and must be related to muscular layer of
vessel walls and nerve supply to vessels. Stress that vessels are supplied only by sympathetic nerve fibers and
mention the vasomotor center at this time.
Aging of Arteries
Distinguish carefully between the terms arteriosclerosis and atherosclerosis.
Arrangement of Vessels in the Body
Help students understand these circulations: pulmonary circulation, coronary circulation, and systemic
circulation. The importance of safety belt and air bags is discussed in a sidebar on p. 717.
An interesting homework assignment is to have students trace the circulation of a red blood cell from one specific
location in the body to another. Be sure to include the heart and lungs in the path. This will help students learn
the circulatory pathways. They can also include the functions of the RBCs in different areas.
Homeostasis
Dynamics of Blood Circulation
Students must be able to describe the significance of these physical factors on circulation of blood: viscosity,
laminar and turbulent flow, blood pressure, rate of blood flow, Poiseuille’s law, critical closing pressure,
Laplace’s law, and vascular compliance.
Blood Pressure Measurement
It is important for students to understand the equipment, the physical, and the physiological factors used to
measure blood pressure before they learn the clinical technique. After the description of how blood pressure is
measured, discuss the different factors that can cause variations in blood pressure such as sex, age, body size,
health and fitness.
Pulse
The pulse is important clinically because one can determine heart rate, rhythmicity, and other characteristics by
feeling it. Use the Clinical Focus: Pulse, p. 746, to provide information.
Capillary Exchange and Regulation of Interstitial Fluid Volume
The Process Figure 21.32, Fluid Exchange Across the Wall of Capillaries, p. 747, can help students understand
this. Edema is an important health topic and a sidebar on p. 748 provides information.
Control of Blood Flow in Tissues
Table 21.15, Homeostasis: Local Control of Blood Flow, p. 750, is a good tool to help students understand this
topic. This shows regulations by metabolic need of tissues, nervous mechanisms, hormonal mechanisms,
autoregulation, and long-term local blood flow.
Regulation of Mean Arterial Pressure
Mean arterial pressure (MAP) is proportional to cardiac output times peripheral resistance. The Homeostasis Fig.
21.37, Baroreceptor Effects of Blood Pressure, p. 756, and Homeostasis Figure 21.39, Effects of pH and Gases on
Blood Pressure, p. 758, will help students understand this topic. Remind students that the Process Fig. 21.35,
Baroreceptor Reflex Control of Blood Pressure, p. 754, is similar to the process figure in Chapter 20. Added are
the sympathetic nerves to the blood vessels. The Homeostasis Fig. 21.42, Control of Blood Pressure Long-Term
(Slow-Acting) Mechanisms, p. 763, illustrates the kidney’s and the heart’s function in long-term control.