Relaxation of the heart (diastole)

- Ventricles + atria relax - Higher pressure in pulmonary artery + aorta closes the SL valves to prevent backflow into ventricles - Blood returns to heart - Atria fill again due to higher pressure in vena cava + pulmonary vein - Increases pressure of atria - Ventricles continue to relax, pressure falls below pressure of atria - AV valves open - Blood flows passively into ventricles from atria - The atria contract, whole process starts again