Question

Which of the following occurs during depolarization of a cardiac​ cell?

A. Potassium moves into the cell.
B. The cell becomes relatively more positively charged.
C. The cell becomes negatively charged.
D. Sodium moves out of the cell

Answer 1

During depolarization, the cell becomes relatively more positively charged due to the influx of sodium ions, moving the membrane potential closer to zero.

Step-by-step explanation:

During depolarization of a cardiac cell the correct option is B. The cell becomes relatively more positively charged. This is because of the influx of sodium (Na+) ions into the cell. The concentration of Na+ is higher outside of the cell, and when the voltage-gated sodium channels open, Na+ rushes into the cell due to both the concentration and the electrical gradient, since the interior of the cell is typically slightly negatively charged compared to the outside. The entry of positively charged Na+ ions makes the inside of the cell less negative and moves the membrane potential closer to zero, which is the essence of depolarization.