Restoration of a Physiological Function

the renewal of normal cellular activity in a differentiated cell. Coordinated physiological functioning in the whole body is restored as cells replace their various components, including energy-providing and supportive structures, through the vital process of protein synthesis. Restoration of a function relies on the close interconnection between the genetic apparatus of a differentiated cell and that cell’s specific physiological function.

In some differentiated cells, proteins and the structures that they form are degraded soon after synthesis (for example, the life-span of mitochondria in liver cells is six or seven days). Yet the structure and function of the differentiated cell are maintained over a long period of time. This maintenance of structure and function is possible because the degradational processes are practically completely balanced by the activity of the cell’s genetic apparatus, which directs the synthesis of specialized cell proteins and thus provides for the replacement of degraded structures. The restoration process is complete and physiological functioning is maintained at a stable level if the intensity of protein synthesis constantly meets the demand that is set by the intensity of functioning and the rate of degradation of structures.

Information from the cytoplasm informs the nucleus of the level at which a specific physiological function is maintained; this information acts as a feedback mechanism that regulates the activity of the genetic apparatus and prevents the degradation of all structures. Through its influence on the genetic apparatus, the level at which functioning is maintained is a determining factor in the restoration of a physiological function. Thus, protein synthesis and energy transformation in the differentiated cells of an organ are controlled by the intensity at which the cellular structures function, and this intensity’s effect on the activity of the genetic apparatus is the mediating factor. Activation of the genetic apparatus in response to intensification of functioning ensures that the cells continue to fulfill their specific, differentiated purpose, since the proteins that are synthesized are highly specialized. Furthermore, activation of the genetic apparatus is the mechanism by which cells provide themselves with a greater mass of energy-producing structures than functioning structures.

The relationship between the intensity at which structures function and the activity level of the genetic apparatus controls the restoration of a physiological function and is a necessary link in the mechanism by which an organism adapts to its environment. It has been suggested that many pathological processes are the result of a discrepancy between the intensity of synthesis of specific structural proteins and the intensity of functioning and degradation of cellular structures.