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?

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. (Connects to Chapter 10)

How do pacemaker cardiac muscle cells differ from contractile cardiac muscle cells? What is autorhythmicity?

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

a. The rapid depolarization phase of the contractile cell action potential is due to the opening of voltage-gated potassium ion channels.

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

b. Pacemaker cells lack a distinct plateau phase.

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

c. The plateau phase in contractile cells is due to the influx of calcium ions through calcium ion channels.