Abstract
Approximate equations describing the absorption and elimination processes of gases, which bind with hemoglobin, in living boby have been derived. Theoretical values obtained from the equations are compared with corresponding various experimentally determined values. Both the values agree quite well for carbon monoxide, indicating the validity and versatility of the equations. It has been shown that the rate of both the processes is proportional to the (alveolar ventilation per minute/total oxygen capacity of blood) ratio. The difference in the ratio should be carefully taken into account when one compares the results obtained on different animal species. For nitric oxide considerable discrepancies are observed between the theoretically predicted values and experimental results, strongly suggesting the conversions of the oxide in living body. This lead to the proposal of a hypothetical scheme for the metabolism of inhaled nitric oxide.