Blood can be defined as a tissue that is made up of white blood cells, platelets, plasma, red blood cells and other components. About 1-1½ gallons (4 to 6 liters) of blood is circulated in the body and the heart pumps the whole volume of blood every minutes.
Thus, blood is known to deliver oxygen and nutrients to the rest of the body while waste products and carbon dioxide produced were removes from the body. During metabolism, oxygen is transported in the blood from the lungs to the cells of the body while carbon dioxide during these processes is transported back to the lungs by the blood.
However, blood also play other important functions in the body by regulating acid-base (pH), electrolytes and temperature.
