100 



(a) 



VERTEBRATE RESPIRATION 



©2 



Chloride 

 shift 



Lung 



C02 C02 



Plasma 



HbOo' ♦ CO, 



C02 



Ho CO, ^> HoO ♦ CO, 



2 .3 CARBONIC ^ 2 



ANHYDRASE 



(b) 



Red blood corpuscle 

 Tissues 



02 02 



Plasma 



kco,,H,o5!£iS;^H2co3. 



A )k 



^2 ♦ n2<- 



Carbamino- 

 Haemoglobin 



■HbCOo ♦ O- 



H*» HbOj 



CO2 ♦ HjO 



CARBONIC ANHYDRA 



.H2C03->-H*» HCO3 



r\Chloride 

 shift 



Red blood corpuscle 

 Fig. 28. 

 Diagrams to illustrate the role of the red blood corpuscles in the 

 transport of oxygen and carbon dioxide, (a) in the lungs, (b) in the 

 tissues. 



of positive ions in the corpuscle, and there is an inward move- 

 ment of chloride ions. This is the only way equilibrium can be 

 established because the red blood cell membrane is relatively 

 impermeable to positive ions. This exchange is called the 

 'chloride shift' and serves the useful purpose of allowing a great 

 deal of bicarbonate to be carried in the plasma. 



In the lungs the haemoglobin takes up oxygen and the pro- 

 portion of oxyhaemoglobin within the corpuscle is increased. 



