The human circulatory system provides oxygen and nutrients to the cells and tissues, and removes carbon dioxide and waste products.
Oxygen enters the lungs where it passes into the blood stream via the capillaries. It then enters the heart in the form of oxygenated blood that is pumped throughout the body. Carbon dioxide as a waste product of respiration is carried from the tissues back to the lungs where it is excreted.
Food is ingested then broken down into nutrients (digested) in the digestive system where the nutrients are absorbed into the blood stream. The nutrients are carried by the circulatory system to all of the body’s cells and tissues.
Waste products of metabolism are carried from the tissues by the circulatory system to the liver where they are detoxified. The detoxified wastes are then carried to areas where they are excreted in the form of carbon dioxide from the lungs, perspiration on the skin, feces in the digestive tract and urine formed by the kidneys.
Thus, the circulatory system facilitates the major body functions of respiration, metabolism and excretion.
Main function of Circulation in the body is to make available oxygen and nutrients to all cells of the body and disposal of the wastes of the body through kidney.