DIGESTION ..ill 



some of the carbohydrates. Invertase changes sucrose to 

 dextrose and levulose; maltose changes maltose to dextrose; 

 and lactase changes lactose to dextrose and galactose. 



Pancreatic juice is secreted by the pancreas, which is a 

 long flattened gland, and is discharged into the intestine 

 like the intestinal juice when food reaches the stomach. 

 Pancreatic juice is a clear, viscid, decidedly alkaline liquid, 

 containing in addition to water a little organic matter and 

 inorganic salts of which sodium carbonate is the most 

 important and which gives alkalinity to the juice. Pan- 

 creatic juice contains the principal digestive enzymes of the 

 alimentary canal. 



Amylopsin is the pancreatic amylase which hydrolyzes 

 starch to maltose, being much more energetic in action than 

 ptyalin. An alkaline solution is necessary for it to act. 



Steapsin is the pancreatic lipase which hydrolyzes fat 

 to glycerine and fatty acids. The fatty acids thus liberated 

 unite with the alkalies which are present in the juice of the 

 intestine to form soaps. It is not definitely known whether 

 all fats are thus hvdrolvzed or whether a part of the fat is 

 so changed and the remainder emulsified in the soap solution. 

 The former is the more probable, however. This enzyme 

 also is onlv active in an alkaline solution. 



Trypsin is the pancreatic protease which hydrolyzes 

 proteins in the alkaline medium and changes them to pep- 

 tones and possibly to amino-acids. Trypsin is much more 

 energetic in its action than is pepsin in the stomach and the 

 probabilities are that it hydrolyzes the proteins more com- 

 pletely. 



Bile is a fluid secreted by the liver and discharged into 

 the small intestine together with intestinal juice and pan- 

 creatic juice when food is received into the stomach. It is 

 a thin liquid somewhat viscid, of bitter taste, and very 

 alkaline due to the presence of sodium carbonate and sodium 

 phosphate. It varies in color from greenish yellow to 

 brownish red, depending on the animal. In herbivorous, or 

 plant-eating animals, it is greenish in color; in carnivorous, 

 or meat-eating animals, it is orange or brown. There are 

 present in the bile in addition to the normal secretory 



