Blood performs the following functions :

1. Transportation of oxygen.

2. Transportation of carbon dioxide.

3. Transportation of various hormones.  

4. Healing up of injured parts : At the point of injury, clotting occurs and thus the blood helps in healing up of the injured part.

5. Transportation of the metabolic waste products : The blood takes metabolic waste products from all cells and supply them to kidneys.

6. Antibodies : The antibodies of plasma neutralize the toxic substances produced by bacteria.

7. Protection from diseases : The neutrophils engulf the foregin bacteria and thus protect human beings from diseases.

8. Distribution of various nutrients throughout the body.