The functional role arises from the way the body part is built. For an instance, the arrangement of bones and muscles in the human hand with its long jointed fingers, make grasping possible. Also, the heart's powerful muscular wall can contract and propel blood out of the chambers into the blood vessels and heart valves preserve blood moving in the appropriate direction. Other examples could be: a shoulder rolling in its socket, an elbow bending, and a bicep pulling up on a forearm to lift an object.
