The diaphragm separates the thoracic cavity containing the heart and lungs, from the abdominal cavity and performs an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs.he superior surface of the dome forms the floor of the thoracic cavity, and the inferior surface the roof of the abdominal cavity. As a dome, the diaphragm has peripheral attachments to structures that make up the abdominal and chest walls.
A American Heart Association-Stroke Association answered. The four valves in your heart are made of thin (but strong) flaps (cusps) of tissue that open and close as your heart pumps. They make sure that blood flows through your heart in the right direction. Your valves work hard as they stretch back and forth with every heartbeat.
There are 4 valves in the heart: tricuspid, pulmonary, mitral, and aortic. In the United States, surgeons perform about 106,000 heart valve operations each year. Nearly all of these operations are done to repair or replace the mitral or aortic valves. These valves are on the left side of the heart, which works harder than the right. They control the flow of oxygen-rich blood from the lungs to the rest of the body. See also on this site: Valve Disease.