THE LIVER 257 



ward direction. A secondary kinking, therefore, is brought 

 about at the termination of the duodenum, which, in turn, 

 becomes abnormally distended and reacts on the stomach. 

 The absorption of toxic material from the loaded bowel gives 

 rise to serious symptoms, and the condition has been termed 

 chronic intestinal stasis. 



When no obstruction is present in the small intestine, a 

 bismuth meal should reach the caecum within five hours. 



The Lymph Vessels of the small intestine terminate in the 

 mesenteric glands (p. 256), which send efferents to join the 

 lymph glands associated with the abdominal aorta. 



THE NERVE-SUPPLY OF THE SMALL INTESTINE is derived 

 from sympathetic fibres which have their centres in the lower 

 thoracic segments of the spinal medulla. In addition, the 

 duodenum and the first coils of the jejunum probably receive 

 some of the terminal branches of the vagi. 



Referred pain in connexion with the small intestine is 

 usually experienced in the umbilical region (Fig. 96), but, 

 owing to the great length of the gut, the presence of areas of 

 cutaneous hyperalgesia is not of the same diagnostic value as 

 it may be in gastric disturbances. 



The mucous membrane of the small intestine secretes the 

 succus entericus, which takes an active part in the digestion 

 of carbohydrates. It contains enzymes which convert di- 

 saccharids into monosaccharids, rendering them ready to be 

 absorbed by the blood-vessels in the wall of the gut. 



In addition, the succus entericus contains a substance, 

 termed secretin^ which normally stimulates the flow of the 

 pancreatic secretion (p. 270). Further, the succus entericus 

 affects proteid metabolism by converting the inactive 

 trypsinogen of the pancreas into trypsin, which has a powerful 

 proteolytic action. 



THE LIVER 



The Liver occupies practically the whole of the right hypo- 

 chondriac region and the upper part of the epigastrium, and 

 17 



