ADAPTATION TO HEIGHT

From Big Medical Encyclopedia

ADAPTATION TO HEIGHT — physiological process of adaptation of a human body and animals to living conditions and vigorous activity with the lowered partial pressure of oxygen (ro2) in inhaled air. And. by century under natural conditions it is more correct to call highlands acclimatization (see) since in mountains, in addition to the lowered partial pressure of oxygen in air, the temperature schedule, high ultra-violet radiation, etc. exerts impact on an organism. At this unequal weather conditions in mountains, for example on Pamir and in the Caucasus, cause various reactions of an organism at ascension on the same height.

The term «adaptation to height» more approaches those cases when the forehead or an animal rises a century by height in a nonhermetic cabin of the aircraft or is affected lowered ro2 in experimental conditions (in a pressure chamber).

Early studies And. by century in mountain conditions domestic scientists last century Albitsky, V. I. Kushelevsky, N. N. Tretyakov, A. N. Lavrinovich, etc. saw off). Influence lowered ro2 in simulated conditions (the special camera) was studied by the French scientist P. Bert. (See Height) and studying of mechanisms of high-rise adaptation were carried out to the Soviet period of a research of influence of height on an organism by N. N. Sirotinin in the Caucasus, M. F. Avazbakiyeva, K. Yu. Akhmedov, M. M. Mirrakhimov, L. G. Filatova and other pases Pamir and Tien Shan. At the end of 30 — the beginning of 40 20 century very much a lot of work on studying of mechanisms of Adaptation is carried out by one of founders of the Soviet air medicine V. V. Streltsov who made the first rise in a pressure chamber and also the staff of department of normal physiology of BMA of S. M. Kirov under the leadership of the academician L. A. Orbeli — M. P. Brestkin with employees and employees Ying-that an air medicine of I. P. Pavlov A. P. Apollonov, V. G. Mirolyubov, M. I. Waqar, D. I. Ivanov other.

Mechanisms A. by century in the conditions of a pressure chamber are intensively studied. During the studying of essence of mechanisms A. by century two levels of adaptive reactions appear: the first — system and the second — fabric or cellular. At the system level in adaptive reactions the respiratory system (increase in volume of lung ventilation, increase in number of the opened alveoluses and change of permeability of their walls), cardiovascular system (increase in cardiac performance, redistribution of blood — increase in blood supply of a brain, heart and liver due to decrease in blood supply of other bodies and fabrics) and system of blood participate (increase in oxygen capacity of blood originally by emission in a circulatory bed of the deposited erythrocytes with the subsequent strengthening of an erythrogenesis in marrow etc.). These adaptive reactions are directed to «fight for oxygen», and for delivery of necessary amount of oxygen to cells for maintenance of normal life activity contrary to lowered ro 2 in inhaled air. Adaptive reactions are caused reflex, and cells of c are originally excited. N of page and vocational receptor educations, you sokochuvstvitelny to change ro 2 in blood. On fabric, or cellular, level adaptive processes happen in cells of various fabrics, including and in cells of c. N of page. In animal experiments it is established that in cells there are adaptation processes, on the one hand, directed to fight for oxygen, and with another — increasing portability of oxygen insufficiency. Treat the adaptation processes directed to fight for oxygen: increase in oxygen capacity of fabrics (increase of maintenance of a myoglobin), increase in activity of a number of enzymes of oxidizing metabolism, increase of content of mitochondrial protein, emergence of ability of fabrics to the increased utilization of oxygen from the environment with reduced partial pressure, change of biochemical and biophysical properties of erythrocytes and fractional composition of hemoglobin. Stimulation of processes of anaerobic glycolysis increases portability of an acute hypoxia (see).

Noted phenomena in cells form gradually, not earlier than 10 — 20 days from the beginning of influence of a hypoxia (in animal experiments). As a rule, to this term decrease in initial tension in work of functional systems, improvement of the general condition of an organism is observed. It is possible to assume that adaptation reactions at the cellular level play an essential role in establishment of new level of a homeostasis (see) and regulation of functional systems of c. N of page. The mechanisms regulating cellular adaptation reactions experimentally are almost not studied. The important role in this regulation of trophic influences central and the autonomic nervous system and hormones of hemadens is supposed.

It is essential that result of adaptation reorganization at the system and cellular levels is increase in resistance of fabrics (including c. N of page) but only to an acute hypoxia, but also to some other disturbing factors. It is shown that the animals adapting to a hypoxia within 4 — 6 weeks become more resistant to ionizing radiation, overcooling, a poisoning with cyanides and the poisons of the central action causing spasms to burns, infections, a hyperoxia etc. Such results were received irrespective of whether adaptation to a hypoxia in mountains or in a pressure chamber was carried out. Thus, the high-rise training applied for development And. by century, increases the general stability of an organism. From this point the niya very important task is represented to a zra working off and observance of the optimum modes of a high-rise training. At disturbance of the optimum modes of a high-rise training «adaptation disease» can develop, at a cut the general stability of an organism decreases. At the person only the system level of adaptation is studied rather well.

It is found that at permanent residents of highlands adaptation reactions in functional systems are expressed to a lesser extent, than at the people who for the first time rose by heights from sea level and who lived in mountains several weeks and even years.

It is possible to assume that at permanent residents of highlands fabric adaptation has bigger specific weight. However for the present poorly experimental material confirming justice of this hypothesis. But it is already known that at inhabitants of the Peruvian Andes (height to 4500 m) the increased maintenance of a myoglobin and a superactivity of a number of respiratory enzymes in skeletal muscles is observed. Similar data are obtained at the mountain animals and animals trained to a hypoxia in a pressure chamber [Reynafarye]. The materials received at inspection of biochemical properties of intercostal muscles of the people having inborn hypoxemic («blue») heart disease (biopspya are interesting during surgical correction of inborn defect). Such patients almost from the moment of the birth live in conditions of a hypoxia. It turned out that biochemical properties of muscles of such persons are essentially similar to properties of skeletal muscles of the animals adapted to a hypoxia in a pressure chamber or in mountains. It is known also that the Peruvian Indians living and working in mines at height of 4500 m are capable to perform big physical activity with considerably smaller power consumption and accumulation milk to - you, than living at sea level [Hurtado]. It demonstrates that at inhabitants of highlands it was created and genetically special nature of metabolic processes was fixed in a lineage. Development of aircraft, astronautics, development of mountain riches, work at mountain astronomical and meteorological stations, development of mountaineering cause the necessity of further studying of mechanisms A. by century.

Bibliography: Avazbakiyeva M. F. Influence of climate of Kazakhstan and Kyrgyzstan on a human body, Alma-Ata, 1958, bibliogr.; Akhmedov K. Yu. Breath of the person at a mountain hypoxia, Dushanbe, 1971, bibliogr.; Barba-sh about in and 3. I. Acclimatization to a hypoxia and its physiological mechanisms, M. — L., 1960, bibliogr.; it, Dynamics of increase in resistance of an organism and adaptive reactions at the cellular level in the course of adaptation to a hypoxia, Usp. fiziol. sciences, t. 1, K» 3, page 70, 1970, bibliogr.; Van Lear E. I am Stikney K. Gipoksiya, the lane with English, M., 1967; World' M. M rakhim. Cardiovascular system in the conditions of highlands, L., 1968, bibliogr.; Simanovsky L. N. A role of neurohormonal reaction in adaptation to a hypoxia, Usp. owls of river biol., t. 68, century 6, page 434, 1969, bibliogr.; Filatova L. G. Researches but physiology of high-rise acclimatization of animals and person, Frunds, 1961; High altitude physiology, ea. by. R. Porter a. J. Knight, Edinburgh — L., 1971; Iiurtado A. Aclimatacitfn a la altura, Buenos Aires, 1966; Reynafarje B. Myoglobin content and enzymatic activity of muscle and altitude adaptation, Appl. Physiol., v. 17, p. 301, 1962.

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