Plasma, which is 90% water, constitutes about 55% of blood volume. Plasma contains:
- Albumin - the chief protein constituent
- Fibrinogen - responsible in part, for the clotting of blood
- Globulins - including antibodies and other clotting proteins.
Plasma serves a variety of functions, from maintaining a satisfactory blood pressure and volume to supplying critical proteins for blood clotting and immunity. It also serves as the medium of exchange for vital minerals such as sodium and potassium.