The vascular system, also called the cardiovascular system, is responsible for routing blood to various parts of the body. The blood carries essential nutrients and oxygen to all of the cells of the body. As the heart beats, it pushes blood out through a large blood vessel on the top of the heart called the "aorta." The "arteries" carry oxygen-rich blood away from the heart. These are represented by the red vessels in the multimedia slide. After delivering their cargo of oxygen and nutrients to the various tissues of the body, the arteries give way to "veins" which then carry the waste products back to the heart so they can be expelled by the lungs. The oxygen-deficient blood carried by the veins is represented by the blue vessels in the slide.