DIASTOLE (RELAXATION)

Phase when ventricles relax to allow in order to allow blood to flow in.

When they relax their volume incresaes while pressure  decreases.

Atrio-ventricular valve/tricuspid opens allowing deoxygenated  blood from body  tissues to flow into the right ventricle while oxygenated blood flows from the left atrium into the left ventricle.

Semi-lunar valves close preventing the blood flowing back into the ventricles.Slight contractions of auricles forces blood to flow into the ventricles.