The transport/circulatory system in human beings consist of the following three parts:
(i) Blood: The blood is the medium for transportation of all kinds of materials like oxygen, carbon dioxide, digested food and waste material from one part of the body to the other.
(ii) Blood Vessels: The intricate network of blood vessels consisting of arteries, veins and capillaries run through the entire body and the transportation of materials like oxygen, carbon dioxide, digested food and waste material from one part of the body to the other takes place through the blood vessels only.
(iii) Heart: The heart pumps the blood through the blood vessels. Deoxygenated blood containing Carbon dioxide reaches the heart from different parts of the body and is pumped to the lungs through veins for releasing carbon dioxide and absorption of oxygen. Oxygen-rich blood reaches the heart from the lungs and is pumped through arteries to the tissues and organs where oxygen is required.