Functional Properties of Cardiac Muscle

The functional properties of cardiac muscle differ from the skeletal muscle in two important respects. One is that, when a contraction starts in one area of the heart muscle mass, it rapidly spreads throughout the muscle mass. During contraction the cell membrance of the cardiac muscle fibres undergoes electric changes, known as action potentials.

The second peculiarity of the heart muscle is that, the cell membrane after completion of an action potential remains in a refractory state for a long enough time to allow the muscle to relax. Because of this refractory period, the cardiac muscle cannot go into a sustained contraction. The refractory period is thus essential for the alternation between contraction and relaxation vis-a-vis normal rhythmic contraction of the heart.