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 bloodVenous blood
 Partial pressure (mm of mercury)Content as % of volumePartial pressure (mm of mercury)Content as % of volume
  Dissolved formBonded form Dissolved formBonded form
Oxygen ................90-1000.2818-2035-450.1212-15
Carbon dioxide ................37-412.5-2.644-4842-472.8-3.048-53
Nitrogen ................560-58010560-58010
Other gases ................tracetracetracetrace

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.