You are an athletic trainer who is working with someone planning to run a marathon. Your trainee tells you to give him a workout that will make his heart 'beat faster than ever before.' What do you tell him about the effects of too rapid a heart rate?

The pericardial cavity is located between:

a. The parietal pericardium and the fibrous pericardium.

b. The fibrous pericardium and the myocardium.

c. The parietal pericardium and the visceral pericardium.

d. The epicardium and the endocardium.

Which of the following statements is true?

a. The tricuspid valve is located between the right atrium and the right ventricle.

b. The mitral valve is located between the pulmonary veins and the left atrium.

c. The pulmonary valve is located between the pulmonary artery and the pulmonary veins.

d. The aortic valve is located between the right ventricle and the aorta.

Mr. Watson has been diagnosed with mitral insufficiency, or a malfunctioning mitral valve, which causes the valve to not close properly. Predict the signs and symptoms you might expect from a disease of this valve. What would happen to the patient's stroke volume and cardiac output? Explain. What might help improve his cardiac output?

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The heart plays a role in the regulation of blood pressure and secretes the hormone atrial natriuretic peptide.

A newer drug, ivabradine, lowers the heart rate by blocking the nonselective HCN cation channels. Why would this action decrease the heart rate? Would this drug have an effect on pacemaker cells, contractile cells, or both? Explain.

An experimental toxin makes the refractory period of cardiac muscle cells equal in length to that of skeletal muscle fibers. Predict the consequences of this toxin.