What does a longer refractory period in cardiac cells ensure?

A longer refractory period in cardiac cells is crucial for maintaining the heart's proper rhythm and function. This period is the time during which the cardiac muscle cells are unresponsive to further stimulation after an initial contraction. By ensuring that cardiac cells cannot be re-excited immediately after an action potential, the longer refractory period prevents the possibility of constant or inappropriate contractions, known as tetany, which could lead to ineffective pumping of blood.

This mechanism allows the heart to fill with blood properly between beats and ensures that the contraction and relaxation phases occur as needed for efficient circulation. As a result, the heart is able to maintain a rhythmic and coordinated contraction pattern, which is essential for effective cardiac output and overall cardiovascular health.