The document describes the structure and function of the human heart. It outlines the four chambers of the heart - right atrium, left atrium, right ventricle, and left ventricle. It notes the interatrial and interventricular septums that separate the chambers. Four valves are described - tricuspid, mitral, pulmonary, and aortic valves. The document explains that during diastole the heart fills with blood while during systole the ventricles contract to pump blood out of the heart.