From Big Medical Encyclopedia

DEFENSE REACTIONS OF THE ORGANISM — the physiological, biochemical and morphological reactions (reflex and humoral) arising in response to actions of the irritants having the harmful or damaging character. Biol, value 3. the river of the lake consists in ensuring optimum constancy of internal environment of an organism (see. Homeostasis ). These reactions are a product of evolutionary development and have species-specific properties. Principle of the organization 3. the river of the lake at all levels biol, systems (an organism, systems of bodies, bodies, fabrics, cells) consists in perception and reflection of the acting agent, in recovery fiziol, parameters of an organism.

For understanding of the principles of integration biol, systems at implementation 3. the river of the lake is important the theory of functional systems of P. K. Anokhin, according to a cut «selection» and integration of separate links of functional system submits to the principle of useful adaptive effect (see. Functional systems ). Net result of action any 3. the river of the lake is preservation of the main fiziol, constants of an organism.

Majority 3. the river of the lake having system character is carried out on the basis of the reflex principle. At the same time the afferent link is presented by the respective receptive field (skin, mucous membranes, the peripheral ends of exteroceptive analyzers, reflexogenic zones of vascular system etc.). The central link can be located at the different levels of a head and spinal cord. An efferent part of a reflex arc of defense reaction is presented by the corresponding motor, ferruterous, vascular device (motor reactions, dacryagogue, salivation, pressor depressory reactions, release of hormones etc.). However many defense reactions on the mechanism can have local (local) character and proceed due to reactivity of peripheral structurally functional educations.

3. rubles of the lake of various type are inherent digestive, cardiovascular, circulatory, respiratory and to other systems. In system of digestion 3. the river of the lake is shown at action on the receptive field of a mucous membrane of an oral cavity, gullet, stomach and other bodies of a digestive tract of the irritants which are initially programmed as rejected. Defense slyunootdelitelny reaction consists in plentiful salivation, promoting dilution and removal of the rejected substance from a mucosal surface of a cover of a mouth. On the basis of this inborn reaction uslovnoreflektorny can be developed. Defense reaction of peloric department of a mucous membrane of a stomach consists in production of the viscous slime having alkali reaction. This slime neutralizes an acid gastric juice and by that protects a mucous membrane of a stomach. System defense reaction of all device of digestion is observed as a stage of acute gastritis. It is shown in braking of gastric secretion and appetite. Defense reaction of a small intestine at intoxications and infections is shown in strengthening of secretory and peristaltic activity that promotes removal of the irritating agents. The emetic reflex also belongs to defense reactions of the alimentary system (see. Vomiting ).

Defense respiratory responses (see. Cough , Asthma , Sneezing ) provide removal of mechanical particles from respiratory tracts and promote maintenance of datum level of gas exchange. Have protective value also secretory reaction of a mucous membrane of upper respiratory tracts and bronchial tubes, napr, at change of structure of a gaseous fluid. Inhalation of the concentrated vapors of ether, chloroform, ammonia leads to a reflex apnoea (apnoea).

Reactions of protective character are observed also in system of blood. So, decrease in partial pressure of oxygen in inhaled air causes defense reaction from red blood (production of erythropoetins, increase in quantity of erythrocytes) that promotes increase in oxygen capacity of blood and neutralization of the operating factor.

At a certain stage of evolution of animals 3 appeared. river of the lake on pain stimulation (see. Pain ). This reaction has the complete integrated character, and various systems of an organism take part in its course.

3. rubles of the lake combine in themselves also adaptive and compensatory reactions to extraordinary irritants of exteroceptors and interoceptors. Adaptive reactions are a part such patol, processes as an inflammation, a hypoxia, fevers. Process of antibody formation under the influence of effect of antigen also belongs to adaptive reactions.

The mobilizing role in the organization of protective and adaptive reactions belongs to sympathetic department of century of N of page. (L. A. Orbeli, 1938), and also to the adrenergic, neurochemical device (P. K. Anokhin, 1957).

New opportunities for understanding of the mechanism 3. rubles of the lake appeared as a result of G. Selye's works. According to its theory, the leading role in the organization adaptation syndrome (see) systems possess a hypophysis — bark of adrenal glands and to other hemadens. This syndrome has nonspecific character since directly does not depend on quality of the extraordinary damaging agent who caused it.

The special category is made by reactions immunobiol, the device of an organism which cause specific resilience to microbic, virus agents and toxins (see. Allergy , Antibodies , Inflammation , Immunity , Phagocytosis ).

Along with the general (nonspecific) adaptive reactions specific reactions which depend by nature operating irritant are observed. So, e.g., at blood loss certain adaptive reactions are observed: tachycardia, increase in blood pressure, mobilization of the deposited blood (see. Blood loss ). Under the influence of pathogenic factors at first there is the most dynamic general adaptive reaction in the form of excitement of c. the N of page, a cut is followed by strengthening of function of the endocrine device, separate bodies and metabolic rate. At the expressed insufficiency of these reactions excitement of c. the N of page is replaced by braking, a cut it is possible to interpret as a last resort of protection of an organism against action of extraordinary pathogenic factors. Increase in stability of an organism in the conditions of braking of c. by N of page it is connected with change of metabolic processes in tissue of a brain, oppression of oxidizing phosphorylation, restriction of disintegration of makroergichesky phosphoric connections. At animals braking of c. the N of page facilitates work of a brain in the conditions of insufficient blood supply. Braking as the adaptive reaction which arose in the course of evolution is shown at zimnespyashchy animals.

Protective and adaptive reactions (see), arising in the course patol, process, are often insolvent in maintenance of a homeostasis though they can be shown stronger, than at usual conditions of existence of an organism. So, at a sharp stenosis of a trachea, despite considerable strengthening of respiration intensity, there are an anoxemia and a hypercapnia.

Compensatory reactions accompany 3. river of the lake usually at long action of pathogenic factors. E.g., compensatory hyperfunction and a hypertrophy of a myocardium arise at heart diseases, strengthening of function of one of pair bodies at loss of function of another (a hypertrophy of one kidney after removal another).

Thus, the organism has a wide range of the defense reactions providing normal course of functions and a homeostasis. However at action of the excessive and long damaging irritants there occurs «failure» of protective and adaptive mechanisms that is shown in emergence patol, states (see. Disease ). See also Protective reflexes (in pathology) , Compensatory processes .

Bibliography: Ado A. D. General allergology, M., 1970, bibliogr.; E Alperi. Inflammation, M., 1959, bibliogr.; Anokhin P. K. Biology and neurophysiology of a conditioned reflex, M., 1968, bibliogr.; Gelgorn E. and Lufbor-r about at J. Emotions and emotional frustration, M., 1966, bibliogr.; Lishshak K. and E N d r yo c and AA. Neuroendocrinal regulation of adaptation activity, the lane with Wenger., Budapest, 1967; The Multivolume guide to pathological physiology, under the editorship of H. N. Sirotinina, t. 1, page 9, M., 1966, bibliogr.; About r e of l and L. A. Lectures on physiology of a nervous system, L., 1938, bibliogr.; P and in l about in I. P. Complete works, t. 3, book 1 — 2, M. — L., 1951; Petrov I. R. The general adaptive reactions at action to an organism of harmful irritants, Vestn. USSR Academy of Medical Sciences, No. 5, page 87, 1962; With e of l E. Sketches about an adaptation syndrome, the lane with English, M., 1960, bibliogr.

F. P. Vedyaev, R. U. Lipschitz.