Bloo plasma is the liquid component of blood, in which the blood cells are suspended. It makes up about 55% of total blood volume. It is comprised of mostly water (90% by volume), and contains dissolved proteins, glucose, mineral ions, hormones, carbon dioxide (plasma being the main medium for excretory product transportation), as well as the actual blood cells. Blood plasma is prepared simply by spinning a tube of fresh blood in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off. Blood serum is blood plasma without fibrinogen or the other clotting factors.