Substantial atrial to ventricular put off. This will allow the atria to completely empty their contents into the ventricles; simultaneous contraction might purpose inefficient filling and backflow. The atria are electrically isolated from the ventricles, linked simplest through the AV node which briefly delays the sign.
Coordinated contraction of ventricular cells. The ventricles must maximize systolic pressure to force blood through the circulate, so all the ventricular cells ought to paintings collectively.
Ventricular contraction starts at the apex of the coronary heart, progressing upwards to eject blood into the outstanding arteries. Contraction that squeezes blood closer to the go out is more green than a easy squeeze from all guidelines. Although the ventricular stimulus originates from the AV node inside the wall setting apart the atria and ventricles, the Bundle of His conducts the sign to the apex.
Depolarization propagates thru cardiac muscle very swiftly. Cells of the ventricles settlement nearly simultaneously.
The movement potentials of cardiac muscle are unusually sustained. This prevents premature rest, retaining preliminary contraction till the complete myocardium has had time to depolarize and settlement.
Absence of tetany. After contracting, the coronary heart should relax to fill up again. Sustained contraction of the coronary heart with out relaxation could be fatal, and this is avoided by way of a temporary inactivation of certain ion channels.