Use the diagram of an action potential to answer the following questions.

-Phase 0 of the action potential shown is produced by an

Question

Use the diagram of an action potential to answer the following questions.
 
-Phase 0 of the action potential shown is produced by an

Quizplus · Accepted Answer

[Chapter 3, III C 1 a]. Depolarization, as in phase 0 , is caused by an inward current (defined as the movement of positive charge into the cell). The inward current during phase 0 of the ventricular muscle action potential is caused by opening of $\mathrm{Na}^{+}$channels in the ventricular muscle cell membrane, movement of $\mathrm{Na}^{+}$into the cell, and depolarization of the membrane potential toward the $\mathrm{Na}^{+}$equilibrium potential (approximately $+65 \mathrm{mV}$ ). In sinoatrial (SA) cells, phase 0 is caused by an inward $\mathrm{Ca}^{2+}$ current.

Use the Diagram of an Action Potential to Answer the Following