Plasma is the liquid component of blood, in which the blood cells are suspended. It is yellow in color. Plasma makes up about 55% of total blood volume, and is composed of mostly water (90% by volume). Plasma carries not only the blood cells but also nutrients (sugars, amino acids, fats, salts, minerals, etc.), waste products (CO2, lactic acid, urea, etc.), antibodies, clotting proteins (called clotting factors), chemical messengers such as hormones, and proteins that help maintain the body's fluid balance.