The cardiovascular system consists of the heart, blood vessels (arteries, veins, and capillaries), and the approximately 5 liters of blood that the blood vessels transport. This system transports oxygen, nutrients, hormones, and cellular waste products throughout the body. The cardiovascular system is powered by the heart, which is only about the size of a closed fist. Even at rest, the average heart easily pumps over 5 liters of blood throughout the body every minute.
To learn more about how the circulatory system works, please click here for an article from Pacific Medical Training.