What does repolarization refer to in cardiac terms?

Repolarization in cardiac terms specifically refers to the process where cardiac cells return to their resting state following depolarization, which involves a change in the electrical charge across the cell membrane. During repolarization, the ions return to their original state, primarily sodium ions leave the cell and potassium ions return, restoring the negative internal charge relative to the outside of the cell. This process is crucial for the heart's normal rhythm, allowing it to prepare for the next contraction. Understanding this concept is fundamental in cardiology and plays a significant role in interpreting an electrocardiogram (ECG), where repolarization is represented by the T wave.

It is important to differentiate this from the other concepts listed. The process of contraction in the heart is known as depolarization, not repolarization. A buildup of electrical charge typically refers to the state before repolarization and does not accurately describe the events during the repolarization phase itself. The excitation of the heart muscles relates to depolarization, which triggers contraction, rather than the return to a resting state that characterizes repolarization. Thus, option A accurately captures the definition and significance of repolarization in cardiac physiology.