The marrow within bones fulfills an important function called , which is the creation of blood cells.

The major function of bone marrow is to generate blood cells. ... Bone marrow mesenchymal stem cells (multipotent stromal cells) produce the non-blood cell components of marrow, including fat, cartilage, fibrous connective tissue (found in tendons and ligaments), stromal cells that support blood formation, and bone cells.

delegated (sometimes called enumerated or expressed) powers are specifically granted to the federal government in article i, section 8 of the constitution. this includes the power to coin money, to regulate commerce, to declare war, to raise and maintain armed forces, and to establish a post office.