The circulatory system transports blood, nutrients, gases, and wastes throughout the body via a network of tubes called blood vessels. The heart pumps blood through this closed system. Blood carries oxygen, glucose, waste products like carbon dioxide and urea. The circulatory system includes arteries, veins, capillaries, blood, the heart, lungs, kidneys and digestive system. The heart has four chambers that pump oxygenated and deoxygenated blood to the body and lungs respectively. Blood pressure measures the force exerted by blood on artery walls and has a normal systolic and diastolic range.