Plasma is the liquid component of blood that holds the blood cells in suspension. It makes up 55% of the blood's total volume and is mostly composed of water (92%) and dissolved proteins (8%). Plasma carries nutrients, hormones, carbon dioxide, and oxygen to tissues and transports waste products away from tissues. It plays a vital role in maintaining electrolyte balance and protects the body from infection. Plasma is separated from blood cells when a tube of blood is spun in a centrifuge.