The right ventricle is filled by the blood from the right atrium, passing through the tricuspid valve. The tricuspid valve gets its name from its 3 valve cusps, which is an AV valve. Strong tendinous cords named chordae tendineae help the cusps of the AV valve hold in position. By cone-shaped papillary muscles, the chordae tendineae are second to the ventricular walls. As an umbrella in a strong wind, these structures prevent the AV valves from everting when the ventricles contract.
The tricuspid valve is led to close and the blood led to leave the right ventricle through the pulmonary trunk and to enter the lungs through the right and left pulmonary arteries by the ventricular contraction. Positioned at the base of the pulmonary trunk is the pulmonary semilunar valve, and there it prevents the backflow of ejected blood into the right ventricle.
Oxygenated blood is conveyed to the left atrium via 4 pulmonary veins, 2 from each lung after gas exchange has happened within the capillaries of the lungs. The blood is received by the left ventricle from the left atrium. The bicuspid valve (mitral valve) divides these 2 chambers. This AV valve is open to permit blood to flow from the the atrium to the ventricle when the left ventricle is relaxed; and the bicuspid valve closes in order to prevent the backflow of blood into the atrium when the left ventricle contracts.