Types of Blood. Blood is a specific body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including the transfer of oxygen and nutrients to the lungs and tissues. Making blood clots to prevent blood clots. The blood that passes through the veins, arteries, and capillaries is known as whole blood, a mixture of about 55% plasma and 45% blood cells. About 7 to 8% of your body weight is blood. An average-sized...