A theoretical model of the respiratory function of blood.

The model of the respiratory function of blood as outlined here is judged to be a powerful tool for the evaluation of the potential effects of changes in blood as well as tissue parameters upon the supply of oxygen to tissue. The erythrocyte-plasma disequilibria in lung and systemic capillaries which is a consequence of the slowness of plasma CO2 hydrolysis are not significant in terms of the delivery of oxygen to tissue, but result in slightly lower unloading of CO2 in the lungs compared to that which might occur at full equilibration. However, the effects might be of greater interest when relating pH values measured by in vivo sampling to actual values prevailing within the capillaries. The physiological importances of hyperventilation and elevated DPG levels in anemia cannot as yet be clarified. If anything, it appears that increased DPG is a compensatory mechanism to restore proper O2-Hb affinity in alkalosis, while the purpose for an alkalosis is not obvious.