Final answer:
Plasma proteins such as albumin, globulins, and fibrinogen perform key functions including maintaining osmotic pressure, substance transport, immunity, and blood clotting. Albumin is the most abundant and contributes significantly to osmotic pressure, whereas globulins, including antibodies, transport substances and play roles in immunity. Fibrinogen is crucial for clotting.
Step-by-step explanation:
The known functions of proteins normally present in plasma include several vital roles such as maintaining osmotic pressure, transporting substances, and immunity. Albumin is the most abundant plasma protein and is chiefly responsible for the osmotic pressure of plasma. Besides contributing to osmotic pressure, globulins, which are comprised of alpha, beta, and gamma subtypes, have distinct functions such as transport of iron, lipids, and fat-soluble vitamins, and the gamma globulins function specifically as immunoglobulins or antibodies, which are antigen-specific proteins produced by specialized B lymphocytes. Finally, fibrinogen, another plasma protein produced by the liver, is critical for blood clotting processes.