Atrioventricular and Semilunar Valves

Although adjacent myocardial cells are joined together mechanically and electrically by intercalated discs (chapter 12; see figs. 12.31 and 12.32), the atria and ventricles are separated into two functional units by a sheet of connective tissue—the fibrous skeleton previously mentioned. Embedded within this sheet of tissue are one-way atrioventricular (AV) valves. The AV valve located between the right atrium and right ventricle

Test Yourself Before You Continue

1. Using a flow diagram (arrows), describe the pathway of the pulmonary circulation. Indicate the relative amounts of oxygen and carbon dioxide in the vessels involved.

2. Use a flow diagram to describe the systemic circulation and indicate the relative amounts of oxygen and carbon dioxide in the blood vessels.

3. List the AV valves and the valves of the pulmonary artery and aorta. How do these valves ensure a one-way flow of blood?

4. Describe the structure of the fibrous skeleton of the heart. What is the significance of this structure?

Heart and Circulation 381

Systole

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■ Figure 13.11 A photograph of the aortic and pulmonary semilunar valves. The valve flaps are shown in their closed position.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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