Systole and diastole ae two phases in the cardiac cycle.These
occur when heart beats and pumps blood to different parts of the
body through blood vessels.
- Systole occurs when heart contracts to pump the blood out
.During systole ventricular voume decreases and blood pressure
increases.Atrioventricular valves are closed and semilunar valves
are opened ,atria relax and they are filled with blood.Pulmonary
trunk and aorta stretch and first heart sound (lub) is heard.
- Diastole occurs when heart relaxes after contraction.During
diastole recoil of pulmnary trunk and aorta occurs and second heart
sound(dub) is heard.Ventricles relax ,semilunar valves are closed
and atrioventricular valves are opened,Ventricular volume increases
and blood pressure decreases.