The Mechanism of development of a mountain disease

The dry free air contains: nitrogen of 78,08 %, oxygen-20,94 of %, carbonic acid-0,03 of %, argon-0,94 of % and other gases-0,01 of %. At rise on height this percentage parity(ratio) does not change, but the density of air, and consequently, and magnitudes of partial pressure of these gases changes.

Under the law of diffusion gases pass from medium with higher partial pressure on medium with lower pressure. Respiratory metabolism both in lungs, and in a blood of the person is carried out owing to available. Differences of these pressure. At normal atmospheric pressure of 760 mm pт.ст. The partial oxygen tension makes: 760Х0,2094=159 mm hg, where the 0,2094 percent maintenance(contents) of oxygen in an atmosphere, peer 20,94 %.

In these conditions the partial oxygen tension in alveolar air (inhaled with air and getting in alveoluses of lungs) makes about 100 mm hg Oxygen we shall badly dissolve in a blood, but he is bound by fiber of the hemoglobin which is being red bloody balls-эритроцитах. Under ordinary conditions owing to high partial oxygen tension in lungs the hemoglobin in an arterial blood is sated(saturated) with oxygen up to 95 %.

At passage through capillaries of tissues the hemoglobin of a blood loses about 25 % of oxygen. Therefore the venous blood carries z to itself up to 70 % of oxygen, which partial pressure, as it is easy to be convinced from the schedule (fig. 2), makes during the moment pritekanija a venous blood to lungs upon termination of a cycle of a circulation only 40 mm hg Thus, between venous I the arterial blood exists the appreciable pressure difference peer 100-40=60 mm hg

Between Carbonei dioxydum inhaled with air (partial pressure of 40 mm hg), and Carbonei dioxydum, pritekajushchej with a venous blood to lungs upon termination of a cycle of a circulation (partial pressure of 47-50 mm hg), pressure difference makes 7-10 mm hg

As a result of existing difference of pressure oxygen passes from air cells in a blood, and is immediate in tissues of an organism this oxygen from a blood diffuses in cells (on medium with lower partial pressure). Carbonei dioxydum, on the contrary, all over again from tissues passes in a blood, and then, at the approach of a venous blood to lungs,-from a blood in alveoluses of a lung, whence she and exhausts in ambient air (fig. 3).

Drawing 3С an ascention on height partial pressure of gases decrease. So, at height of 5550 m (that corresponds(meets) to atmospheric pressure of 380 mm hg) for oxygen it peerly

380Х0,2094=80 the mm hg, that is decreases twice. Thus, naturally, the partial oxygen tension and in an arterial blood therefore decreases not only saturation of a hemoglobin of a blood by oxygen decreases, but also due to sharp reduction of a difference of pressure between an arterial and venous blood transition of oxygen from a blood in a tissue considerably(much) worsens. So there is the oxygen insufficiency-гипоксия, able to lead to disease of the person by a mountain disease.

It is natural, that in an organism of the person there are series of protective компенсаторно-adaptive reactions. So, first of all the disadvantage of oxygen leads to exaltation of chemoceptors-nervous of the cells very sensitive to depression of partial oxygen tension. Their exaltation serves as a signal for an excavation, and then and an acceleration of respiration. The event thus a lung expansion enlarges their alveolar surface and promotes that to faster saturation of a hemoglobin by oxygen. Owing to this, and also series of other reactions in an organism a plenty of oxygen acts.

However with intensifying respiration ventilation of the lungs at which there is a strengthened deducing(removing) ("illuviation") of Carbonei dioxydum from an organism is enlarged. This phenomenon especially amplifies at an intensification of work in conditions of high mountains. Tax if on plain in a state of rest within one minute from an organism leaves approximately 0,2 l СО2, and at the intense work--1,5-1,7 l in conditions of high mountains on the average for a minute the organism loses nearby 0,3-0,35 l CO2 in a state of rest and up to 2,5 l at the intense muscular work. As a result in an organism there is disadvantage СО2-так the named hypocapnia, described depression of partial pressure of a carbon dioxide in an arterial blood. But in fact the carbon dioxide plays important, a role in adjustment of processes of respiration, a circulation and oxidation. Serious disadvantage CO2 can lead to a paralysis of the respiratory center, to sharp fall of arterial pressure, deterioration of work of heart, to disturbance of nervous activity. So, depression of arterial pressure СО2 on magnitude from 45 up to 26 m.m hg reduces a circulation of a brain almost half. That is why in the carboys intended for respiration at greater(big) heights, fill not pure(clean) oxygen, and its(his) admixture from 3-4 % of a carbon dioxide.

Dropping of maintenance(contents) СО2 in an organism breaks an acid-base balance aside excess of alkali. Trying to restore this equilibrium, kidneys within several days usilenno delete from an organism together with urine this as though excess of alkali. That reaches(achieves) an acid-base balance at new, lower level which is one of the basic attributes of end of the period of adaptation (partial acclimatization). But thus it is broken magnitude of an alkaline reserve of an organism (decreases). At disease by a mountain disease decrease of this reserve promotes its(her) further development. It speaks that sharp enough decrease of quantity(amount) of alkali reduces ability of a blood to bind acids (including lactic acid), formed at hard work. It in short term changes an acid-base parity(ratio) aside excess of acids which breaks work of some enzymes, the most important leads to disorganization of process of a metabolism and, the seriously ill patient has an inhibition of the respiratory center. As a result respiration becomes surface, the carbon dioxide is short deduced(removed) from lungs, collects in them and interferes with access of oxygen to a hemoglobin. Thus quickly there comes a dyspnea.
From all told follows, that though a principal cause of occurrence of a mountain disease is the disadvantage of oxygen of tissues of an organism (hypoxia), but enough greater(big) role is played here also with a disadvantage Carbonei dioxydums (hypocapnia)