The components of the transport system in human beings are the heart, blood, and blood vessels. The function of the heart is to pump oxygenated blood throughout the body and receives deoxygenated blood from the various body parts and sends this impure blood to the lungs for oxygenation. Blood has three main functions: transport, protection, and regulation. Blood transports the following substances: Gases, namely oxygen (O
2
​
) and carbon dioxide (CO
2
​
), between the lungs and rest of the body. Nutrients from the digestive tract and storage sites to the rest of the body. The function of blood vessels is to transport blood throughout the body.