1. Structures of the Heart

2. Valves Valves are structures that allow blood to flow through only one way (in one direction) when the heart contracts. They open when the heart contracts, and close when the heart relaxes.

3. Tricuspid Valve Valve that separates right atrium from right ventricle. When the atriums contract, it opens and blood is pushed through. When the ventricles contract, it closes and does not allow blood to flow through.

4. Pulmonary Valve Valve that separates the right ventricle and the pulmonary artery. Valve opens when the ventricles contract and closes when ventricles relax.

5. Mitral Valve Valve that separates left atrium from the left ventricle. When the atriums contract, it opens and blood is pushed through. When the ventricles contract, it closes and does not allow blood to flow through.

6. Aortic Valve Valve that separates the left ventricle and the aorta. Valve opens when the ventricles contract and closes when ventricles relax.