The circulatory system circulates blood around the body, carrying oxygen, nutrients, waste, and more. Powered by the heart, which pumps blood, the circulatory system includes blood vessels that transport blood. The heart is a muscle about the size of a fist located in the chest center left that works as two pumps - the right side receives blood from the body and sends it to the lungs, while the left side receives blood from the lungs and pumps it to the body.