Final answer:
The semilunar valve is a type of heart valve located between the ventricles and their associated arteries. It prevents backflow of blood and ensures one-way flow. The pulmonary semilunar valve is between the right ventricle and the pulmonary trunk, and the aortic semilunar valve is between the left ventricle and the aorta.
Step-by-step explanation:
The semilunar valve is a type of heart valve found between the ventricles and their associated major arteries. The pulmonary semilunar valve is located between the right ventricle and the pulmonary trunk, while the aortic semilunar valve is situated between the left ventricle and the aorta. The semilunar valves prevent the backflow of blood into the ventricles, ensuring that blood flows in one direction.