he cardiovascular system consists of heart,blood vessels, and the approximately 5 liters of blood that the blood vessels transport. responsible for transporting oxygen, nutrient, hormones, and cellular waste products throughout the body, the cardiovascular system is powered by the body's hardest-working organ-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