Chapter 19. The Cardiovascular System: The Heart

19.0 Introduction

This photo shows a human heart.

Figure 19.01: Human Heart This artist’s conception of the human heart suggests a powerful engine—not inappropriate for a muscular pump that keeps the body continually supplied with blood. (credit: Patrick J. Lynch)

Chapter Objectives

After this chapter, you will be able to:

19.1 Describe the location of the heart and its internal and external features

19.1 Describe the path of blood through the cardiac circuits

19.1 Explain how blood flows through the coronary circulation and why this is necessary for cardiac function

19.2 Describe the anatomy of  cardiac muscle

19.2 Explain how the cardiac conduction system controls cardiac muscle contraction

19.2 Describe the process and purpose of an electrocardiogram

19.3 Summarize and explain the connection between the various events of the cardiac cycle

19.4 Describe factors that effect cardiac output and be able to calculate it

19.4 Describe the effects of exercise on cardiac output and heart rate

19.4 identify cardiovascular centers and cardiac reflexes that regulate heart function

19.4 Describe how heart rate, stroke volume, contractility, and the Frank-Starling mechanism affect cardiac output

19.4 Identify the factors affecting heart rate and stroke volume

19.5 Describe fetal heart development

In this chapter, you will explore the remarkable pump that propels the blood into the vessels. There is no single better word to describe the function of the heart other than “pump,” since its contraction develops the pressure that ejects blood into the major vessels: the aorta and pulmonary trunk. From these vessels, the blood is distributed to the remainder of the body. Although the connotation of the term “pump” suggests a mechanical device made of steel and plastic, the anatomical structure is a living, sophisticated muscle. As you read this chapter, try to keep these twin concepts in mind: pump and muscle.

Although the term “heart” is an English word, cardiac (heart-related) terminology can be traced back to the Latin term, “kardia.” Cardiology is the study of the heart, and cardiologists are the physicians who deal primarily with the heart.