Circulatory System and Cholesterol

The circulatory system is one of the most important because, by keeping blood circulating throughout the body, it provides each cell with the oxygen and nutrients it needs, while also removing waste products generated within cells as part of metabolism. It also plays a role in transporting other substances, such as hormones, and in defending the body against pathogens. The heart is the main organ that makes up the circulatory system; the blood, the fluid pumped throughout the body, and the blood vessels are the circuits through which it travels.