Il6 THE PHYSIOLOGY OF DIGESTION AND ABSORPTION 



through the alimentary canal allows their more ready disinte- 

 gration. 



3. It aids in the emulsification of fats. 



4. It promotes the absorption of fats. Recently the state- 

 ment that the bile promotes all kinds of absorption has appar- 

 ently been successfully disproved, but it seems certain that "the 

 bile acids enable the bile to hold in solution a considerable 

 quantity of fatty acids, and possibly this fact explains its connec- 

 tion with fat absorption." (American Text-Book.) 



The Secretion of the Intestines. 



The intestinal secretion, or succus entericus, is a product of 

 the crypts of Lieberkuhn and Brunner's glands. It is scanty, of 

 a yellow color and an alkaline reaction. Opinions vary as to 

 what foods are affected by this fluid, but since the more recent 

 experiments have overcome some difficulties in obtaining speci- 

 mens, the conclusions based upon them seem most reliable. It is 

 said to have no effect on proteids or fats. It contains an amylo- 

 lytic enzyme, which aids the pancreatic juice in converting 

 starch into maltose. It also has an enzyme, invertase, which 

 converts cane sugar into dextrose and levulose, as well as an allied 

 enzyme, maltase, which converts maltose into dextrose. The 

 carbohydrates are absorbed as dextrose, with the probable excep- 

 tion of lactose. It is mainly cane sugar, maltose (from starch) 

 and lactose that are in the alimentary tract and require to be thus 

 changed to dextrose. 



It is not out of place to say that ptyalin produces maltose and a 

 little dextrose, and that the pancreatic juice and succus entericus 

 produce maltose and considerable dextrose. The maltose is 

 converted into dextrose during the process of absorption. It is, 

 therefore, customary to say that the carbohydrates are absorbed 

 only as dextrose. 



Movements of the Small Intestine. The effect of intestinal 

 movements is to force the contents onward through the ileocecal 



