Plasma is the fluid part of the blood in which the blood cells and the platelets are suspended. It consists of water in which many chemicals are dissolved, including proteins, salts, sugars, nitrogenous wastes, and carbon dioxide. Plasma is differnet from serum, which is the fluid that remains when the blood is clotted; serum is plasma without fibrinogen and the other components of a blood clot.

Plasma is the main medium for the transportation of substances throughout the body. It carries nutritive substances to the body structures and removes their waste products. Plasma also makes possible chemical communications within the body by transporting hormones.

Plasma may be given by transfusions to patients who have lost serum through burns. It also may be used to treat shock or disorders in which protein is lost from the body, such as ascites and nephrosis.