Читать книгу General system theory of aging. Special role of the immune system - V. I. Dontsov - Страница 16

A fully formed organism has many non-updated elements at all its hierarchical levels: unique genes, non-dividing cells (for example, nerve cells, including autonomic control centers), non-regenerating structures of organs (alveoli, nephrons, etc.), organs themselves and etc.

The loss of these elements with age is probabilistic, and therefore in the simplest case, it is described by the same type of formula as the loss of overall viability:

dX / dt = -k * X,

where X is the number of non-updated elements of the body.

Graphs of total aging (mortality) for Gompertz and mortality associated with a decrease in viability due to the loss of non-renewable elements, therefore, should coincide and is exponent.

It is known that the loss of alveoli, nephrons with age, reaches 50%, and that of nerve cells in the hypothalamic regulatory centers – 80% (which links this mechanism with the regulatory mechanism of aging). In nature, the stochastic mechanism of aging is fully realized in postmitotic animals (for example, in Drosophila), in which there are practically only non-updated structural units.

The death of elements is the extreme expression of the mechanism mentioned, which, in general terms, leads to changes in the elements of any system. With age, individual structures in the body can not only die, but also change due to accumulating micro- and macro- damage, or change the structure and function of adaptation.

Due to the non-ideal selection mechanisms and self-renewal of such structures in the body, these structures accumulate with age (increase in the number of old, incapacitated cells in all organs and tissues, degeneration, accumulation of mutations in the genome, decrease in the number and quality of sperm cells, accumulation of sclerotic elements in tissues, etc.); the functions of such structures are usually reduced. The accumulation of damaged elements is probabilistic in nature; therefore, the decrease in the number of normal, intact elements with age is described by the same type of formula as the Gompertz formula for loss of general viability.

The main role in the elimination of damage is played by the mechanism of cell division, therefore the deterioration of this process manifests itself morphologically in the form of a wide variety of tissue changes – changes in the forms and sizes of subunits, atrophy, hypertrophy of functional tissue, replacement with nonfunctional connective tissue elements, etc. This is the basis of an increase in morphological (and functional) diversity at the tissue level observed with age and a decrease in their functions. This mechanism underlies such a typical aging phenomenon as atrophy of tissues consisting of constantly self-renewing cells (for example, skin).