The Circulatory System—the Body's Moving company
The Circulatory System—the Body's Moving company The circulatory system is an organ system that includes the heart, the blood vessels, and the blood itself. It has three functions: • to transport materials (i.e., nutrients and oxygen) and cells from one place to another • to defend the body against invasion by harmful organisms by taking white blood cells to an area of injury or infection • to maintain a constant body temperature Your body has a closed network of blood vessels—hollow tubes—that move blood and nutrients. A pumping organ—the heart—pushes blood through this network of vessels.