The cardiovascular system is made up of the heart, blood, and blood vessels, and is responsible for transporting nutrients, gases, and wastes to and from cells, aids in fighting disease and helping to stabilize body temperature. The process by which this is all achieved consists of systemic circulation--when oxygenated blood is pumped away from the heart to the body and returns deoxygenated blood back to the heart--and pulmonary circulation--when oxygen-depleted blood is pumped away from the heart to the lungs and returns oxygenated blood back to the heart.