Step-by-step explanation:
Refractory period is period of the time during which organ or cell is not more capable of repeating an action. It can also be said as amount of the time, the organ takes for the excitable membrane so that it can be as ready for a second stimulus as once it returns to the resting state by following an excitation.
Refractory period in the cardiac physiology is related to ion currents flow into and out of cell freely.
The long refractory period of the cardiac muscle helps to excite heart before proceeding of contraction, which enables heart to pump the blood and to relax then which then to be filled with the blood in cardiac cycle.