Plasma Protein Metabolism

Figure 1 shows a generalized plasma protein system in which Pp is the total amount of a particular protein in the plasma; P{ the total amount of this protein in the interstitial fluids; S, the rate of protein synthesis ; j \ Pp, the rate of protein passage from the plasma to the interstitial fluids (e.g., in g/day); j3Pp, the rate of protein catabolism; and j2Pl, the rate of return of interstitial protein, probably primarily by the lymph. For the moment no assumptions are made about the / s . The equations describing the flow of protein through this system are and these equations show that to define this system requires knowledge of the behavior of S, Pp, and P{ and j\,j2 , and j 3 in various physiological and pathological states.