The heart has 4 chambers: right atrium, left atrium, right ventricle and left ventricle.Right atrium - pumps blood from the Vena Cava to the right ventricle.Right ventricle - pumps blood to the lungs.Left atrium - pumps blood - that is returning from the lungs - into the left ventricle.Left ventricle - pumps blood through the aorta which perfuses the whole body.