ASPT EKG Certification Practice Exam

The ability that enables heart cells to contract after receiving an electrical impulse is known as contractility. Contractility refers to the intrinsic capability of the myocardium (heart muscle) to shorten and generate force in response to stimulation. When electrical impulses propagate through the heart's conduction system, they result in depolarization of the myocardial cells, leading to the cross-bridge cycling between actin and myosin filaments within those cells. This process allows the heart cells to contract effectively, pumping blood throughout the body.

While excitability refers to the ability of cardiac cells to respond to stimuli and generate action potentials, this does not directly describe the actual process of contraction. Automaticity describes the ability of certain cardiac cells to generate spontaneous electrical impulses, such as those in the sinoatrial node, which is important for heart rate regulation but not for the contraction itself. Conductivity refers to the heart's ability to transmit electrical impulses through the conduction pathways, which is essential for coordinated contraction, but it is distinct from the forceful shortening of the cardiac muscle itself.