164 



Enzyme 

 Amylase 



Trypsin 



Lipase 



Erepsin 



Invert ase 

 Maltase 



Lactase 



ELEMENTS OF BIOLOGY 



Where Found 



In small intestine, 



part of pancreatic 



juice 



In small intestine, 



part of pancreatic 



juice 



In small intestine, 



part of pancreatic 



juice 



Small intestine 



Small intestine 

 Small intestine 



Small intestine 



Action 

 Converts starch to simple sugars. 



Splits proteins into intermediate 

 compounds. 



Splits fats to fatty acids and 

 glycerin. 



Splits intermediate compounds 

 derived from proteins into amino- 

 acids. 



Digests cane sugar. 

 Converts products of salivary di- 

 gestion to dextrose. 

 Converts milk sugar to dextrose 

 and galactose. 



The absorption of the products of digestion is a continuous proc- 

 ess. Since the chief changes are wrought in the small intestine, ob- 

 viously it is the site of most of the absorption. Absorption of food is 

 completed in the large intestine, where excess water is also ab- 

 sorbed, for the food entering the large intestine is quite fluid 

 (chyle). In the large intestine the contents are normally fermented 

 by bacteria that are always present. It is an open question whether 

 or not the fermentative action in the large intestine is injurious to 

 the human body; at least, the organism has so adapted itself to the 

 presence of these saprophytes that under normal conditions no 

 appreciable ill effects occur. The contents of the large intestine are 

 undigested and unabsorbed food materials, indigestible and insolu- 

 ble contents of the original food, products of putrefaction by bac- 

 teria, cells shed from the walls of the intestine, some few metabolic 

 waste products, and water. The faeces are thus formed in the large 

 intestine and pass into the rectum, a pouching distention of the end 

 of the digestive canal. The evacuation of the faeces is brought about 



