The Heart

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Chapter: Anatomy and Physiology for Health Professionals: The Heart

The human heart pumps blood through the blood vessels. In the capillaries, nutrients, electrolytes, dissolved gases, and waste products are exchanged between the blood and surrounding tissues.

The Heart

The Heart

After studying this chapter, readers should be able to

1. Describe the size of the heart and its location in the thorax.

2. Identify the layers of the heart wall and the function of each.

3. Identify the four chambers of the heart, and list the associated great vessels.

4. Name the four heart valves, and describe the locations and functions of each.

5. Describe the vascular supply to the heart.

6. Identify the electrical events associated with a normal electrocardiogram tracing.

7. Draw a diagram of a normal electrocardiogram.

8. Define cardiac output, and describe the factors that influence this variable.

9. Describe normal heart sounds and define murmurs.

10. Explain the role of the autonomic nervous system in controlling cardiac output.

Overview

The human heart pumps blood through the blood vessels. In the capillaries, nutrients, electrolytes, dissolved gases, and waste products are exchanged between the blood and surrounding tissues. The heart performs an amazing amount of work over a person’s lifetime, beating an average of 70 to 80 times per minute. An adult heart pumps about 4,000 gallons (approximately 8,000 liters) of blood every day. By the time a person reaches the age of 70, the heart will have contracted about 2.5 billion times. The heart beats approximately 100,000 times each day.

Heart rate is affected by emotions and physical stressors. The heart is made up of two pumps. Its right side receives blood that is low in oxygen from the body tissues. It pumps this blood to the lungs to collect oxygen and drop off carbon dioxide. The heart’s left side receives oxygenated blood from the lungs. It pumps this blood to the body to supply the tissues with nutrients and oxygen. The receiving chambers of the heart are its right and left atria. The pumping chambers of the heart are its right and left ventricles. The heart requires approximately 1/20thof the body’s blood supply even though it makes up only about 1/200th of the weight of the body. The left ventricle is the portion that receives the most blood. 

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