The blood is a specialized connective tissue and performs a very important function in the human system to maintain the homeostasis and life support functions in the human body. It is composed of plasma and formed elements. Liquid part (plasma): This is the liquid portion -- about half -- of your blood: It makes up about 55% of its total volume; the blood cells are suspended in the liquid: It contains water, some salts (sodium and potassium, named for the reactivity of the element), and the chemicals your body needs (nutrients such as glucose, and hormones), and also the wastes your body is getting rid of (like carbon dioxide and ammonia). The other 45% are formed elements (red blood cells, white blood cells, and platelets) each having different, specific purposes and functions to perform Red blood cells are involved in the carrying of oxygen by way of vessels.