Your heart pumps blood constantly through 60,000 miles of blood vessels. Together, the heart, blood, and blood vessels make up the circulatory system. This system delivers oxygen from your lungs to the cells and organs of your body, and helps remove waste products. Readers explore the circulatory system with the aid of numerous photographs and revealing illustrations. This volume also includes information about disorders and diseases of the circulatory system, as well as tips on how to keep the system healthy.