Question

fill in the blank question the heart valves consist of -lined fibrous connective tissue flaps called

Explanation:

Heart valves are composed of endothelium - lined fibrous connective tissue flaps known as cusps. The endothelium is a type of simple squamous epithelium that lines the interior surface of blood vessels and heart chambers, and the cusps are the flap - like structures that control the direction of blood flow through the heart.

Answer:

Endothelium; Cusps