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Text A. Sechenov and His Works on the Blood Gases
IM Sechenov (1829-1905) was a prominent Russian scientist, the founder of Russian physiology and scientific psychology. The range of Sechenov's scientific interests and the number of his research works are really great. 106 scientific works were written by him. In these works he included the findings which he had observed and determined before.
Some of his research works were connected with the investigation of the blood gases and their role in the respiratory process.
IM Sechenov isolated the blood gases and found out that most of the blood gases were combined with erythrocytes. No physiologist had been able to do it before Sechenov. On the basis of his observations IM Sechenov came to the conclusion that hemoglobin was that substance of the blood which accomplished the exchange of oxygen and carbon dioxide in the respiratory process. Physiologists of many countries who had worked on this problem before Sechenov could not estimate the role of hemoglobin in the act of respiration. So the accomplishment of the respiratory process is due to hemoglobin.
I, M. Sechenov investigated the process of absorption of carbon dioxide by the solutions of salts. When he had completed his investigations, he proved that only 2/3 of carbon dioxide were dissolved (soluble) in plasma. The rest of carbon dioxide was combined with red blood cells. The transfer of carbon dioxide from the blood into the lungs was due to the law (the law) of diffusion of gas from fluid into the air. When Sechenov had investigated this phenomenon, he was able to answer the question why oxygen passed into the blood ....
Text B. The Exchange of Gases in the Lungs
The exchange of gases takes place in the alveoli of the lungs. Oxygen passes into the blood and carbon dioxide passes into the atmospheric air.
The exchange of oxygen and carbon dioxide is due to the difference of partial (partial) pressure of these gases in the alveolar air and in the venous blood.
The partial pressure of oxygen in the alveolar air is higher than in the venous blood. The transfer of oxygen from the atmospheric air into the blood is due to this difference of pressures.
The partial pressure of carbon dioxide is higher in the venous blood and this enables carbon dioxide to pass from the blood into alveolar air.
The process of transfer of gases into the medium (Wednesday) with a lower partial pressure is called diffusion. Hemoglobin is that substance of the blood which transfers oxygen in the blood. The oxygen capacity of the blood averages to 18-20 millilitres (ml) per 100 gr of blood. Carbon dioxide is transferred in combination with hemoglobin and as bicarbonic salts.
The combination of oxygen and hemoglobin is called oxyhemoglobin, that of carbon dioxide and hemoglobin - carbohemoglobin.
Text C. The Physiology of the lungs
The physiology of the lungs is associated with their structure. There are over 700,000,000 alveoli in the lungs. The total surface of the alveoli is about 90 sq. m (square metres). The lungs have many capillaries with the total surface of about 80 sq. m. This particular structure of the lungs enables the exchange of gases between the alveolar air and the blood.
Elastic fibers of connective tissue composing the walls of the alveoli, alveolar passages and the visceral pleura enable the lungs to dilate.
When one breathes normally not all the alveoli and capillaries of the lungs are opened. When respiration becomes deep, the number of the opened alveoli and capillaries increases. The flow of blood into the lungs increases when one breathes in and it decreases when one breathes out.