CHAPTER IX. 



THE PRODUCTS OF PANCREATIC DIGESTION. 



After leaving the stomach where the food is subjected to 

 the influences described in the last chapter it passes into the 

 small intestine, where it comes in 1 contact \vith other agents 

 of change. The work in the stomach is largely preliminary 

 and serves to bring the food into a finely divided homogeneous 

 semi-liquid condition, in which it may be readily attacked by 

 the new digestive enzymes. As explained, the chemical actions 

 in the stomach are comparatively simple, and, leaving out of 

 consideration the continuation of the salivary digestion, are 

 due essentially to the combined effect of pepsin, hydrochloric 

 acid and protein substances. In the upper part of the small 

 intestine, however, the work of the pancreatic enzymes is much 

 more complicated; at least three kinds of reactions take place 

 here, due to the three distinct types of ferments in the pan- 

 creatic secretion. The protein digestion begun in the stomach 

 is completed, the carbohydrate digestion begun by the saliva 

 is continued or completed, while the fats, not yet attacked, are 

 brought into a condition of absorption through the intestinal 

 walls. These three groups of changes will be taken up in 

 detail, but something must be said first about the pancreatic 

 juice as a whole. 



COMPOSITION OF PANCREATIC JUICE. 



For obvious reasons it was not possible to give any fair 

 analysis of the gastric juice. But something more is possible 

 in the case of the pancreatic secretion which may be collected 

 by means of a fistula. Most of the experiments have been 

 made with dogs, and the flows collected under conditions to 

 give a secretion as nearly normal as possible show that it con- 

 tains approximately in the mean 90 per cent of water and 10 



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