Patient Care Technician (PCT) AAH Practice Exam

When a cardiac muscle cell is stimulated, what is the cell said to do?

1. Contract

2. Depolarize

3. Repolarize

4. Relax

The correct answer is: Depolarize

When a cardiac muscle cell is stimulated, it undergoes depolarization. This process is crucial for the heart's electrical activity, as it marks the change in membrane potential that occurs when sodium ions enter the cell. Depolarization is responsible for initiating the cardiac contraction, allowing the heart muscle to efficiently pump blood. During this phase, the cell becomes more positively charged, moving away from its resting potential. This is a key step in the cardiac cycle, which subsequently leads to contraction of the heart muscle. While contraction refers to the actual tightening and shortening of the muscle fibers that follow depolarization, the term repolarize describes the process of returning the cell to its resting state after contraction. Relaxation occurs after repolarization when the muscle fibers lengthen and the heart chambers fill with blood. However, it is the depolarization that directly reflects the immediate response of a cardiac cell when it is stimulated.