Plasma is the pale yellowish fluid that holds the blood cells together. It makes up about 55% of the total content of the blood. It contains water, blood clotting factors, proteins (antibodies), glucose, mineral ions, hormones and carbon dioxide, and acts like a medium for their transportation throughout the body. Blood plasma minus all the blood clotting factors is termed serum. It contains only electrolytes, proteins (antibodies) and hormones.
Plasma helps maintain blood pressure and volume. It helps maintain appropriate pH balance in the body. It supplies proteins for blood clotting and immunity, and also serves as the medium for exchange of vital minerals. It can be frozen and preserved after a blood donation and later used for blood transfusion.