1 62 ANATOMY AND PHYSIOLOGY 



What, then, are the uses of the bile which is poured into the in- 

 testine with the pancreatic juice? 



First, it is alkaline in reaction the intestinal enzymes act in 

 an alkaline medium. Second, it holds the soaps in solution, 

 favoring their absorption. Third, it assists the fat-splitting func- 

 tion of steapsin and dissolves fatty acids so that they may be 

 absorbed. Fourth, it accelerates the digestion of fats. Fifth, it 

 delays putrefaction in the intestines, probably in part by assist- 

 ing peristalsis, and thus preventing stagnation of the whole 

 contents. 



Clinical note. Experiment and observation prove that the presence 

 of bile is necessary to nutrition. Without it a person may eat large quanti- 

 ties of food and still lose weight. 



The work of digestion is continued in the jejunum, and to a 

 lesser degree in the ileum. By the absorption of digested food, 

 the intestinal contents are diminished in quantity and changed 

 in character, containing less water and approaching a firmer 

 consistency. 



After passing through the jejunum and ileum into the large 

 intestine, some digestion may still go on by the action of the in- 

 testinal juice which was incorporated with the mass, but the 

 major portion of the contents of the colon consists of undigested 

 remnants and waste. 



From the foregoing we gather the following summary: 



Proteins are digested in the stomach and intestine. The 

 enzymes sue pepsin and rennin, trypsin, and erepsin. Products 

 of protein digestion, peptones and amino-acids. 



Starches are digested in the mouth and the intestine. En- 

 zymes ptyalin in the mouth, and amylopsin in the intestine. 

 Product, dextrose. 



Sugars are digested in the mouth and intestine. Enzymes 

 maltase in the mouth, and maltase and invertase in the intestine. 

 Final product, dextrose. Dextrose (glucose, grape sugar) and 

 levulose taken with the food, do not require to be changed; they 

 are already soluble and absorbable. 



Fa/5 are freed from their connective tissue in the stomach, 

 and split or emulsified in the intestine. Products, glycerine and 

 fatty acids, fat-emulsion. 



