The Circulatory System
The Circulatory System moves blood around your body. This blood carries food and oxygen around to all of the cells of the body. It also carries signals called hormones that help the body work together.
The major organ of the circulatory system is the heart, which pumps the blood. Blood goes away from the heart in tubes called arteries and comes back to the heart in tubes called veins. The smallest tubes are called capillaries.