528 



THE RESPIRATORY EXCHANGE 



The next figure (Fig. 28) gives the dissociation curve of OHb 

 obtained by Loewy in the case of human blood. 



Recent experiments by Bohr, Hasselbalch, and Krogh show 

 that the absorption of oxygen by the blood is influenced by the 

 presence of carbon dioxide ; when the pressure of oxygen is low 



O tension 

 % of atm. 



63-97 O tension 

 in mm. Hg 



e 



5638 



49-77 



42-66 



35-55 



28-44- 



21-33 



14-22 



7-11 



Saturation of Hb 

 FIG. 28. Average Dissociation Curve of OHb in Human Blood (Loewy\ 



and that of carbon dioxide is high the capacity of the blood to 

 take up oxygen is diminished. This factor must, therefore, be 

 taken into account. In Krogh's experiments with horse's blood 

 the pressure of carbon dioxide was maintained at a constant level ; 

 his results are given in the following table of the quantities of 

 oxygen absorbed by the blood at different pressures and at a 

 temperature of 38. 



