List the constituents of plasma and the functions of plasma proteins.
This question was generally well answered. The constituents of plasma include water,
electrolytes, glucose, liver enzymes, urea, creatinine, uric acid, dissolved gases and proteins.
Plasma does not contain any cells. The proteins in plasma are albumin, globulins and
fibrinogen. The globulins include alpha 1 and 2 and beta globulins and gamma globulins.
Examples of α1-Globulins are: α1-fetoprotein, α1-protease inhibitor and prothrombin.
Examples of α2-Globulins include: ceruloplasmin, haptoglobin, α2-macroglobulin and
thyroxin-binding globulin. Examples of β-Globulins are: C-reactive protein, β2-microglobulin
and transferrin. Examples of δ-Globulins are the immunoglobulins , IgG, IgA, IgM, etc. There
are many more other globulins including the coagulation factors, the complement system
and lipoproteins. The functions of plasma proteins include oncotic pressure,
transport/carrier function, role in acid base balance (buffering, CO2 transport) and
proteolytic systems such as complement, kinins, coagulation and fibrinolysis. More
functions include the immune response, enzyme activity eg pseudocholinesterase,
metabolism i.e. plasma proteins can be broken down and contribute amino acids to the
amino acid pool and a role in thermoregulation. Many answers were deficient in details on
the plasma proteins and their functions. The question asked to “list” the constituents, so the
level of detailrequired to score marks reflected this and should have been achievable in the