During the diastole phase, the atrioventricular valves are open while the atria and ventricles remain relaxed. Deoxygenated blood passes through superior and inferior vena cavae and goes back to the right atrium of the heart from the body.
During the systole phase, atrioventricular valves are closed whereas atria and ventricles contract and moves deoxygenated blood to the pulmonary artery and then to the lungs. Blood picks oxygen from the lungs, and then oxygenated blood is sent to the aorta which sends blood to the whole body via blood circulation.
