Exam 1 Review:  Chapter 17:  Plasma Proteins

plasma proteins - The general term for all proteins circulating in the blood (dissolved in the plasma); they are separated by various physical-chemical properties into subgroups:  albumins, and several subgroups of globulins; most are negatively charged (anions) at body fluid pH and most contribute to the buffering of the blood (in toto they are responsible for about 15% of the blood buffering capacity); as a group, they also contribute to blood viscosity and to plasma osmotic pressure; most are synthesized in the liver; many additional functional subcategories are recognized.

albumins - A series of related proteins found in the plasma of various vertebrate species; human albumin is the single largest fraction of the plasma proteins (~60% of total plasma protein and 3.5-5.0 g/dL reference range); therefore it is the major contributor to blood buffering and plasma osmotic pressure; it is also a major transport protein for a wide variety of plasma lipids (fatty acids, bilirubin, etc.) and other molecules with limited water solubility (hormones, urate, etc.); it is a globular protein with a molecular weight of ~66,000 Daltons synthesized in the liver which has a half life in plasma of ~29 days.

globulins - Any of a large family of proteins of a spherical or globular shape which are widely distributed throughout the plant and animal kingdoms; human globulins are the majority of plasma proteins (~35% of total plasma protein and 2.0-3.0 g/dL reference range), most of which are synthesized in the liver; they are separated into several general subclasses by physical-chemical properties: alpha, beta and gamma globulins; the globulins perform a diverse set of activities including regulatory, transport, nutritional, and immune functions; collectively they contribute to blood buffering capacity, blood viscosity and to plasma osmotic pressure.

fibrinogen - A globulin (~4% of total plasma protein and  2-3 mg/mL reference range) synthesized in the liver which is essential for the coagulation of blood (clotting factor I) and is converted to the fibrous protein, fibrin, by the action of thrombin in the presence of ionized calcium.

antibodies = immunoglobulins - Any of a group of large glycoproteins which are secreted by plasma cells; most are negatively charged (anions) at body fluid pH; they make up the bulk of the gamma globulin fraction of the plasma proteins; they are generated in response to specific foreign molecules (antigens) and their main function in the humoral immune response is to bind with their specific antigens; they may also encourage phagocytosis and trigger the complement cascade; there are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, each of which has specific physical-chemical properties and immune functions.

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