Systole is the rhythmic contraction of the heart.
The rhythmic contraction and relaxation of heart muscles is known as ________.
The cardiac cycle is the sequence of events that occurs when the heart beats. In the __(i)_, the heart ventricles ___(ii)___ and helps fill the heart with blood. In the __(iii)_____ the ventricles ___ _(iv)____and pump the blood to the body through the arteries.