Publisher's Synopsis
The circulatory system is made up of five parts: the heart, the lungs, and the capillaries. The circulatory system is closed. The blood is not allowed to enter the circulatory system during circulation. The arterial system is made up of arteries and arterioles, while the venous portion consists of veins and venules. The arterial system carries blood from the heart to the lungs. The veins transport deoxygenated blood back to the heart.