Question

During which phase of the ventricular action potential is the conductance to Ca²⁺ highest?

(A) Phase 0
(B) Phase 1
(C) Phase 2
(D) Phase 3
(E) Phase 4

Answer 1

The conductance to Ca²⁺ is highest during Phase 2 of the ventricular action potential.

Step-by-step explanation:

The conductance to Ca²⁺ is highest during Phase 2 of the ventricular action potential.

In the ventricular action potential, Phase 0 is the rapid depolarization phase, Phase 1 is the early repolarization phase, Phase 2 is the plateau phase, Phase 3 is the rapid repolarization phase, and Phase 4 is the resting phase.

During Phase 2, the slow Ca²+ channels open and Ca²+ enters the ventricular cells, leading to an extended plateau phase and an influx of positively charged ions.