The plateau of the cardiac action potential results from the opening of voltage-gated slow ____ channels in the plasma membrane of the ____ cell.
A)sodium; contractile
B)potassium; autorhythmic
C)calcium; contractile
D)chloride; pacemaker
E)potassium; contractile

Question

Quizplus · Accepted Answer

The plateau of the cardiac action potential is due to the opening of voltage-gated slow calcium channels in the plasma membrane of the contractile cell. Option A and E are incorrect because sodium and potassium channels are responsible for the initial depolarization and repolarization phases of the action potential, respectively. Option D is incorrect as chloride channels do not play a significant role in the cardiac action potential. Option B is incorrect as autorhythmic cells primarily contain voltage-gated calcium channels.

The Plateau of the Cardiac Action Potential Results from the Opening