THE ABDOMEN. 143 



ulcers. There are also the glands of Lieberkiihn which 

 secrete the succus entericus. 



The arteries of the small intestine, which include the 

 superior mesenteric, are from the celiac axis and the 

 nerves are from the superior mesenteric plexus of the 

 sympathetic. The veins empty chiefly into the portal 

 system. 



The movements of the intestine, like those of the 

 esophagus, are peristaltic, but the action is complicated 

 by the fact that the tube is not straight but in coils. 



Intestinal Digestion. The food, which enters the duo- 

 denum as chyme, there comes in contact with the bile and 

 the pancreatic juice, which together but unmixed enter the 

 duodenum from their respective ducts by a common orifice. 

 As in the stomach, the digestive juices are called forth by 

 the presence of food. The bile is secreted in the liver, from 

 which it flows away through the hepatic duct, which joins 

 the cystic duct from the gall-bladder to form the common 

 bile duct. Through this it flows into the intestine during 

 digestion, but between whiles it passes up into the gall- 

 bladder, where it is stored for future use and whence it is 

 expelled when needed. When pure it is a thick, viscid 

 liquid, varying from a bright red to a greenish-yellow in 

 color according to the pigments present, and of an alka- 

 line reaction. It consists chiefly of the bile pigments, 

 biliverdin, which gives the green color, and bilirubin f 

 which gives the red color, and of bile salts in solution. 

 cholesterin, which probably forms the basis of many gall 

 stones, is also present. Bile is a disinfectant to the bowel 

 and a lubricant for the feces. How much digestive 

 action it has is a question, but it affords the necessary 

 alkaline medium for the pancreatic juice to act in. 



The pancreatic juice is secreted by the pancreas, from 

 which it enters the intestine through the pancreatic duct, 

 and is probably the most important fluid in the digestive 

 process. It is clear, practically colorless, slightly viscid 

 or gelatinous, and quite strongly alkaline in reaction, 

 owing to the presence of sodium carbonate. It contains 



