The three major parts of the circulatory system are the heart, blood and blood vessels, according to Hillendale Health. The circulatory facilitates the movement and delivery of oxygen, water and nutrients to the body's cells. This organ system also removes metabolic waste products, such as carbon dioxide, from the blood.
The primary organ of the circulatory system is the heart. It is a four-chambered muscular pump that forces blood to flow within an enclosed circuit of blood vessels, as stated by the University of Minnesota. These tubular structures are classified into three types: veins, arteries and capillaries. Veins transport deoxygenated blood, arteries carry oxygenated blood and capillaries are the conduits for nutrient absorption and gas exchange.
Oxygen-starved blood enters the heart through the right atrium. The blood then flows down into the right ventricle where it is pumped into the lungs to obtain a fresh supply of oxygen in exchange for carbon dioxide, which is expelled through exhalation. Oxygenated blood then flows into the left atrium, moves down to the left ventricle and leaves the heart through the aorta, according to the University of Minnesota. The blood is carried by the arteries to different parts of the body.
A typical adult body contains approximately 5 quarts of blood, as stated by Hillendale Health. This specialized tissue is composed of a liquid matrix called plasma, where highly differentiated cells are suspended. The red blood cells transport oxygen and carbon dioxide in the body. Nutritive components of food are also absorbed into the bloodstream via the capillary walls and circulated throughout the body.