ACID SECRET I OX 421 



to rise and COg has to be retained to preserve the balance at 1/20 

 ]^ut ill doing so, the |H2C'();j] rises, and this will cause the alveolar 

 C'Oa tension to rise. Dodds has shown that tliree-(|uarters of an 

 hour after an average meal the alveolar CO., tension may rise by as 

 nuich as 5 nnn. Hg. In hyperchlorhydria the excessive withdrawal 

 of [Cl]~ from the blood leads to over double this increase of alveolar 

 C"Oo tension. Those suffering from a low concentration of HCl 

 in their gastric juice have a very slight increase in the output of 

 CO2, while achlorhydrics show no change. 



The same problem, that of the secretion of alkali at a later stage 

 of digestion, may be tackled in a similar way. It has been shown 

 by Dodds that during the secretion of the alkaline juices (succus 

 entericus, pancreatic juice and bile) the base of the blood suffers 

 a decrease with a consequent fall in alveolar COg tension. 



Whatever be the mechanism by which these juices are formed, 

 the epithelial cells can remain in contact with a considerable 

 concentration of [H^] or of fOHJ^ without damage. Lowering of 

 vitality, by anaemia, HCN, etc., permits digestion of the walls of the 

 alimentary canal to take place. 



