media10 (1)

The semilunar valves, which are the pulmonic and aortic valves, are crucial as they stop blood from going back into the heart. They act as exit valves to ensure blood flows in the right direction. As I mentioned, the semilunar valves are the ones that prevent blood from flowing back into the heart, so these are the exit valves, the pulmonic and the aortic valves.