The cardiovascular system:

The cardiovascular system, or circulatory system or blood system, is a closed circuit circulatory system that transports blood from the heart to the extremities and various organs and, in return, from these to the heart. It is made up of the heart and the blood vessels that make up the vascular system, with the lymphatic vessels that make up the lymphatic system sometimes associated with it.

The circulation of the blood allows the transport and internal exchange of a wide variety of biochemicals. It helps deliver nutrients, oxygen and hormones to the body's cells. These elements come from the digestive tract, lungs and endocrine glands. The cardiovascular system also collects metabolic waste products from cells, such as carbon dioxide or urea, which are transported to the lungs, liver and kidneys. Finally, it participates in the regulation of many factors, such as the sugar level.