Patient Care Technician (PCT) AAH Practice Exam

In a healthy heart, which phase follows depolarization?

1. Asystole

2. Repolarization

3. Sinus rhythm

4. Contraction

The correct answer is: Repolarization

In the context of cardiac physiology, the phase that follows depolarization in a healthy heart is repolarization. During depolarization, the heart muscle cells undergo a rapid change in voltage, leading to the contraction of the heart muscle. This process is crucial for the heart to pump blood effectively. After the cells depolarize, they need to return to their resting state to prepare for the next heartbeat. This restoration of the resting state is referred to as repolarization. It involves the closing of sodium channels and the opening of potassium channels, allowing potassium to flow out of the cell. This movement of ions results in the membrane potential returning to its baseline level, which is essential for the heart's rhythm and function. Contraction occurs as a result of depolarization, but it does not follow it in an isolated sense; rather, it is part of the same process driven by depolarization. Asystole refers to an absence of electrical activity in the heart, and sinus rhythm describes a normal heart rhythm but does not describe a specific phase following depolarization. Thus, the clear sequence of events recognizes repolarization as the necessary phase that follows depolarization in the cardiac cycle.