The cardiovascular system is also called "circulatory system". It is composed of heart, arteries, capillaries and veins. It is a closed circulating pipeline in which blood flows, supplying oxygen, various nutrients, hormones, etc. to organs and tissues, and transporting the waste of tissue metabolism to the excretory organs, so as to maintain the homeostasis of the internal environment, the progress of metabolism and the maintenance of normal life activities.
