The tricuspid valve is responsible for shutting the upper-right chamber, or atrium, which receives blood from other parts of the body, while the pulmonary valve closes the heart's right ventricle, as the American Heart Association explains. The mitral valve shuts the left atrium, and the fourth valve of the heart, the aortic valve, shuts the lower-left chamber, which holds the oxygen-rich blood before the heart pumps it to the rest of the body.
When the tricuspid valve opens, blood flows from the right atrium to the right ventricle, as described by the American Heart Association. The valve also keeps blood from flowing back to the atrium when the heart pumps blood out of the ventricle. The pulmonary valve opens to allow the heart to pump blood to the lungs through the pulmonary artery, allowing the blood to obtain oxygen.
When the mitral valve opens, blood travels from the left atrium to the left ventricle, according to the American Heart Association. The aortic valve also opens to enable the heart to pump blood from the left ventricle to the aorta and the rest of the body.
Flexibility and correct formation are essential for the proper functioning of the four valves of the heart, as the American Heart Association notes. It is important for the valves to open completely to allow sufficient amounts of blood to travel in and out of the heart. They must also close firmly to prevent blood leaks.