As the heart beats, it pumps blood through a system of blood vessels, called the circulatory system. The vessels are elastic, muscular tubes that carry blood to every part of the body.
Blood is essential. In addition to carrying oxygen from the lungs and nutrients to your body's tissues, it also takes the body's waste, including carbon dioxide, away from the tissues. This is necessary to sustain life and promote the health of all the body's tissues.
