The pumping of the heart is controlled by its own electrical system that coordinates the contractions of the chambers.
The heart has four chambers; the right and left ventricles and the right and left atria. There are four valves that ensure that the blood flows the correct way through the heart and the coronary arteries which supply the heart with its own nutrients and blood supply.
The right atrium receives oxygen-poor blood from all parts of the body and pumps it to the right ventricle. The right ventricle then pumps the blood to the lungs where it absorbs oxygen from the air we breathe. The left atrium then receives the oxygenated blood back from the lungs and then pumps it to the left ventricle. The oxygen-rich blood is then pumped to the body to fuel our muscles and vital organs, keeping us alive and well.