Gases in the Blodo

Gases in the Blodo 

gases dissolved in or chemically bonded with the blood of animals and man.

A complete investigation of gases in human blood was first carried out by I. M. Sechenov in 1859. Blood contains gases that come from the medium surrounding an organism and gases that are generated within the organism. They enter and leave the blood by means of diffusion. The quantity of each of the gases dissolved in arterial blood is determined by its partial pressure in alveolar air and by the coefficient of its solubility in the blood. Oxygen and carbon dioxide, the most important gases in the blood, are found there in both dissolved and chemically bonded states. They form unstable compounds: CO₂ is used in the formation of salts for the blood’s buffer system; oxygen unites with hemoglobin to create oxyhemoglobin. As a result of gas exchange, the content of gases in venous and arterial blood is different (see Table 1).

Should there be any significant change in atmospheric

Table 1. Normal content of gases in human blood
	Arterial blood			Venous blood
	Partial pressure (mm of mercury)	Content as % of volume		Partial pressure (mm of mercury)	Content as % of volume
		Dissolved form	Bonded form		Dissolved form	Bonded form
Oxygen ................	90-100	0.28	18-20	35-45	0.12	12-15
Carbon dioxide ................	37-41	2.5-2.6	44-48	42-47	2.8-3.0	48-53
Nitrogen ................	560-580	1	0	560-580	1	0
Other gases ................	—	trace	trace	trace	—	trace

pressure on the body (for example, in the mountains or in caissons), the partial pressure of O₂ and N₂ changes sharply; this may cause oxygen starvation, caisson disease, and other illnesses. Aside from the gases that are constantly present in the blood, narcotic, toxic, and other gases may enter the bloodstream.

L. L. SHIK