READJUSTMENTS OF REGULATION 33 



10 



30 



30 40 50 6 



^AA*4u^* ej CO, 



70 60 



90 100 



no )30 



Fig. 2. Lower curve absorption of CO2 by blood in pres- 

 ence of air and CO2. Upper curve absorption of CO2 

 by blood in presence of hydrogen and CO2. The line 

 A-B represents the absorption of CO2 within the body. 



therefore represented by the thick line starting at 40 

 mm. which is the pressure of CO2 in arterial blood. 

 This line rises steeply, so that far more CO2 can be 

 taken up by the blood with a given rise of CO2 pres- 

 sure than would be the case if oxyhaemoglobin and 

 reduced haemoglobin had the same effect on the ab- 

 sorption of CO2. It follows also that when the venous 

 blood reaches the lungs and suddenly becomes oxy- 

 genated, the pressure of CO2 in the blood suddenly 

 rises. In this way much more CO2 is given off than 

 would otherwise be the case considering the existing 



