There is a correlation between the intensity of metabolism and the life expectancy of the species concerned. The lack of exercise is forcing the processes of premature aging. The ability to excrete the products of metabolism decreases. It has been proven that microorganisms placed under the influence of the products obtained from their own metabolism die. It was found that in the intestine in a normal state are released ptomaines (toxic amines) primarily in the decay of the proteins. Ilya Metchnikoff experimentally proved that the introduction through the mouth of small quantities of indole and para-cresol leads to senile degeneration of organs and to their physiological sclerosis. In the human body can be formed poisons also in conditions of overheating, of fatigue, in long insomnia, fasting, etc. Lipase in blood is also decreased. It is a digestive enzyme that is secreted primarily from the pancreas. It is involved in the breakdown of fats. This explains the increase in fat deposits in the blood vessels. The content of free cholesterol increased. Reduced activity was noted in salivary and pancreatic glands. Dehydration of the tissue is determined by the reduction of the basic substance (mucoproteins) of the connective tissue that connects the water. The total quantity of iron in the body is also reduced. The formation of "crossed" connections between the giant molecules (proteins, nucleic acids) is inevitable in all cells. The occurrence of "cross-links" is the process by which occur a number of changes in the physico-chemical properties of the two gigantic molecules and which leads to an irreversible condition of "immobilization" of these molecules. This process is very slow and follows a certain path: With age "cross-links" continuously grow and then emerge "heavy", "inert", insoluble proteins and nucleic acids that block intracellular and extracellular spaces. Upon aging the optical activity is continuously lowered. The akrihin blocks the molecules of the respiratory ferment as poison. Studies have confirmed that aging of the body is the result of lowered activity of enzymes. The theory of "cross-links" explains a number of other signs of aging and old age - reduction of biological indicators in stress reactions, the consequences of overfeeding, the impact of certain doses of radiation and others. The formation of "cross-links" is due to hypercholesterolemia (increased levels of cholesterol) in which the lipids of the blood are associated with alpha and beta globulins. Famous is the fact that atherosclerosis as a disease that most oftenly determines the course of the pathological processes of aging in women arises and develops about 10 years later than in men. Therefore we must note the importance of estrogens which keep the development of atherosclerosis.
Excitement (work, motion) drives the cycle of self-renewal with its trace phases - fatigue (parabiosis) and super recovery (exaltation). In lack of working condition (excitement) there will be absent also the cycle of self-renewal, i.e. will occur atrophy and involution. Enhanced function (physical and mental) leads to a state in which the specific functional structural formations within the cell provide "information" which by the cytoplasmic RNA is transmitted to the DNA. Under the influence of this information the DNA (the genetical apparatus of the core) is reconstructed, increases its activity and produces more informational RNA. The latter, in turn, produces a greater amount of proteins needed for structural construction and reinforcement of specific functional structures of the cell. Without functional loading (walking, exercise, work) is not performed also this structural self-renewal, affecting not only the protoplasm but also the core of the cell - carrier of the hereditary genes.
Phenotypic mechanisms of long life, constantly occurring during aging and old age also have adaptive significance. Such mechanisms include, for example - the increase and intensity of glycolysis, increase of the rate of phosphorylation in the cell, activation of some enzymes, the amplified biosynthesis of many proteins, the decrease in activity of the enzymes and the decomposition of some mediators and hormones in a weakened synthesis, the emergence of multi-core cells, the increase in the volume of mitochondria in terms of their quantitative reduction, hypertrophy and hyperplasia of the Golgi apparatus, increase in the surface of the plasmatic membrane, hyperfunction of a number of neurons, myocardiocytes, secretory and other cells in terms of the death of a part of cells, increase in the sensitivity of a number of humoral factors, and many others.