Which term refers to the period when the heart is relaxed and involves repolarization?

The correct term for the period when the heart is relaxed and involves repolarization is "diastole." During diastole, the heart chambers, specifically the atria and ventricles, fill with blood as the heart muscle relaxes. This stage follows the contraction phase, known as systole, where the heart pumps blood out to the body and lungs.

Repolarization refers to the process by which heart muscle cells restore their resting state after depolarization, which occurs during contraction. This is crucial for preparing the heart for the next cycle of contraction. During diastole, the electrical activity represented on an EKG shows the repolarization of the heart muscle, indicating that the heart is getting ready for the next heartbeat.

Other terms such as asystole refer to a complete absence of heart electrical activity, while arrhythmia pertains to irregular heart rhythms, neither of which are related to the relaxation phase of the heart. Systole is directly opposite to diastole, specifically involving contraction rather than relaxation.