From Big Medical Encyclopedia

RESISTANCE OF THE ORGANISM (Latin resistentia resistance, counteraction) resistance of an organism to influence of various disturbing factors.

A human body and animals in the course of phylogenesis gained the morfofunktsionalny properties providing its existence in the conditions of continuous interaction with Wednesday, many factors a cut (physical, chemical, biological) could cause disturbance of life activity, damage and even death of an organism at its insufficient stability — an underdevelopment or weakening of protective mechanisms and adaptive reactions.

The river of the lake is closely connected with its reactivity (see. Reactivity of an organism ). Ability of an organism to resist to the damaging influences finally is defined by its reaction as whole on these influences. The river of the lake, thus, represents one of the main investigations and expressions of its reactivity.

The concept «resistance of an organism» covers a wide range of the phenomena. In some cases it depends on properties of various bodies and systems which are not connected with active reactions to influences. Naira., the barrier properties of many structures interfering penetration through them of microorganisms, alien substances, etc. are considerably caused by their physical features: hypodermic cellulose has good heat-insulating properties; bones, sinews and other fabrics of a musculoskeletal system differ in big resistance to mechanical loadings; the skull is of great importance in protection of a brain against damage etc.

In addition to such, rather passive, mechanisms P. of the lake, adaptive reactions are of exclusively great importance (see. Adaptation ), directed to preservation homeostasis (see) at harmful influences of the environment or at the changes occurring in the organism. These reactions which are the cornerstone of R. of the lake can be inherent everyone defined biol. to a look (specific R. of the lake). So, different types of mammals have unequal poisons resistance (to morphine, a histamine, etc.), to infectious agents, cooling. High specific R. of the lake can be connected or with the special power of protective systems (e.g., high resistance to a bacterial factor at rats), either lack of specialized receptors, or underdevelopment of the mechanisms necessary for implementation corresponding patol. process (e.g., weak expressiveness of allergic reactions at fishes and amphibians).

The river of the lake to various factors can depend on inborn specific features. It is known that even at epidemics caused by very virulent microorganisms (plague, cholera, etc.), not all people who were in close contact with patients get sick, and at the diseased process proceeds not equally. Nek-ry persons of a rezistentna to kinetoza also do not give in to a motion desease; inborn resistance to cooling, overheating, effect of various chemical substances (medicines, poisons, toxins) and to impact of ionizing radiation is various.

Big fluctuations of individual R. of the lake are connected not only with inborn factors, but also with R.'s features of the lake at the time of its interaction with the damaging agent. At the same time the numerous factors changing individual reactivity can raise or lower R. of the lake to this or that influence. R.'s fluctuations by the lake seasonally, within a day are known. Environmental factors have significant effect on R. of the lake. The organism has the greatest resistance at its adequate relationship with the environment. Both insufficient, and excess influences of biologically significant environmental factors lower resistance. E.g., starvation considerably weakens R. of the lake, promoting increase in incidence of infectious and various somatic diseases. Excess food also promotes R.'s decrease of the lake to the factors causing disbolism, functions of closed glands, the blood circulatory system, etc. In a crust, time the great value gets hypokinesia (see), edges R. significantly lowers the lake. However and the overtraining, napr, at athletes, also lowers R. of the lake. Correctly organized socially useful work alternating with rest, normal family and living conditions are important premises of a normal current mental and fiziol. processes also promote the general R.'s increase in the lake. At the same time the lack of positive motivation of work, a constant professional overload, disturbance of biorhythms and other factors promoting psychological traumatization reduce R. of the lake and contribute to various diseases. In the same direction R. of the lake under the influence of such socially mediated harmful factors as alcoholism changes, smoking, drug addiction, etc.

R. of the lake changes in the course of ontogenesis. The newborns who received a stock of antibodies from mother a nek-swarm time are high-resistant to a row inf. diseases. Along with it owing to immaturity of systems of adaptation they differ in hypersensitivity to changes of the environment (cooling, overheating), to malnutrition, water starvation, etc. Further sensitivity to defined inf increases. to factors (children's infections). Instability of neuroendocrinal system is inherent to youthful age, and at the acceleration characteristic of industrialized countries, additional weakening of R. of the lake is quite often observed that promotes emergence of a row nervous and somatopathies. At mature age of R. of the lake the highest. At advanced and senile age in connection with development of atherosclerosis, disturbances of blood circulation, decrease in function of closed glands, an atrophy of fabrics and other processes leading to restriction of functional and structural reserves of an organism the general R. of the lake goes down. However elderly people can be more resistant to action of the factors which are carrying out the pathogenic action through hyper reactions (an allergy, etc.) since ability to such reactions weakens with age. At advanced age the metabolism goes down that can promote R.'s increase of the lake to food and water starvation.

Nek-ry features of R. of the lake are connected with a floor. So, women differ in bigger resistance to a hypoxia, blood loss, injuries. Their hypercholesterolemia is less often observed and later atherosclerosis develops. The biorhythms at women connected with a menstrual cycle significantly change R. to the lake therefore during the nek-ry periods of this cycle of the woman are especially sensitive to mental, infectious and other factors.

Distinguish nonspecific and specific R. of the lake. Specific resistance characterizes high portability only of certain factors of the environment as it is observed at the people who had nek-ry infections (measles, smallpox, etc.), or specially immunizirovanny by vaccines (Immunity, the Infection). The increased resistance to certain factors of the environment forms in process adaptations (see), napr, to conditions of highlands, low temperatures, the raised exercise stresses, etc. At the same time adaptation and high R. of the lake in relation to any influence can be followed by R.'s increase of the lake and to other factors (e.g., to exercise stresses and to a hypoxia). It is possible, however, that successful protection against one category of influences is followed by R.'s decrease of the lake to others; e.g., at adaptation to muscular exercises stability of an organism to a nek-eye to infections and poisons can go down. Mechanisms of specific resistance to microbes and viruses are defined generally by tension humoral and cellular immunity (see).

Lakes usually understand resistance to action of many factors, various by the nature, as nonspecific R., including having extreme character. Very high R. of the lake such characterizes, e.g., astronauts, pilots, divers and representatives of other specialties connected with big and sometimes unpredictable loadings.

Mechanisms of nonspecific resistance did not receive rather full explanation yet. There are in different degree reasonable hypotheses of a role of nek-ry bodies and systems in nonspecific resistance. A. A. Bogomolets, and after G. Selye islands of cortical substance of adrenal glands paid attention to value in R. Its hormones (gluco-and mineralokortikoida) play a big and versatile role in adaptation of an organism to action on it many disturbing factors of the environment. At epinefrektomirovanny animals, as well as at people with insufficiency of cortical substance of adrenal glands, nonspecific R. of the lake turns out lowered what is connected by hl. obr. with a lack of glucocorticoids, requirement in to-rykh for conditions stress (see) considerably increases. In R.'s analysis of the lake the integrating role of various departments of c clearly acts. the N of page of L. A. Orbeli provided convincing proofs of an adaptation and trophic role of a sympathetic part of the nervous system, A. D. Speransky showed participation of various nervous mechanisms in R.'s formation by the lake to poisons, toxins, injuries, and also a role of a nervous system in development of dystrophic processes. Specific mechanisms of nervous control of R. of the lake in many cases are insufficiently clear. However it is undoubted that the response to action of a disturbing factor irrespective of the level of its direct implementation forms as reaction of the complete system which is carrying out the influence on bodies and fabrics through efferent nerves and indirectly through closed glands. The large role is played also by physiologically active agents which are formed in the course of metabolism at reaction of tension and at damage of fabrics. The river of the lake is provided not with any special body or one system, and purposeful interaction of various bodies and physiological systems. At the same time adequacy of regulation and a condition of executive systems (blood circulation, breath, allocation, blood, etc.)* is of great importance. System of cellular immunity, in a cut the large role is played by T - and V-lymphocytes (see. Immunocompetent cells ), and also macrophages (see), has essential value not only in fight against an infection, but also in the general R.'s maintenance by the lake. In particular, it is revealed that the vegetative mutations caused oncogenous substances (see), at normal cellular immunity often do not lead to formation of a tumoral rudiment since mutant cells as alien for an organism are exposed to a lysis.

At the general high nonspecific resistance the organism can be understable to certain influences. In extreme conditions, napr, at astronauts, signs of insufficient resistance of a vestibular mechanism can come to light that leads to disturbance of a number of vegetative functions. Nek-ry persons with very high general resistance do not transfer alcohol owing to low activity of alcohol dehydrogenase.

The state and R.'s features of the lake can be to a certain extent revealed by means of functional trials and loadings, to-rye are used at the prof. selection and in clinic for assessment of functional reserves of bodies and systems. In some cases R. of the lake in relation to certain influences can be estimated direct researches of the most essential components of the systems participating in R.'s formation by the lake (e.g., indicators of immunity). The directed R.'s change by the lake is one of the perspective directions preventive and to lay down. medicine.

See also Locus minoris resistentiae .

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V. K. Kulagin, H. I. Losev.