Question

q. what is the main ion responsible for the plateau phase of the cardiac action potential?
description: sys2 heart obj5b
a. potassium (k+)
b. sodium (na+)
c. calcium (ca2+)
d. chloride (cl-)

Explanation:

During the plateau phase of the cardiac action potential, there is a balance between inward and outward currents. Calcium (\(Ca^{2+}\)) ions enter the cell through L - type calcium channels. This inward \(Ca^{2+}\) current counteracts the outward potassium (\(K^{+}\)) current to maintain the depolarized state (plateau). Sodium (\(Na^{+}\)) is mainly involved in the rapid depolarization phase (phase 0) of the cardiac action potential. Chloride (\(Cl^{-}\)) does not play a major role in the plateau phase of the cardiac action potential.

Answer:

C. Calcium (\(Ca^{2+}\))