1342 



THE ORGANS OF DIGESTION 



this is termed the paranucleus, and it is believed to be an extension from the nucleus. The con- 

 nective tissue among the gland tubules and alveoli presents in certain parts collections of cells, 

 which are termed interalveolar cell islets, or islands of Langerhans. Opie points out that they 

 are most common in the splenic end of the pancreas. The cells of the islands are smaller and 

 paler than the secreting cells of the alveoli, and are arranged in layers with intervening spaces. 

 The islands are sharply demarcated from the alveoli, are much larger than the latter, and are 

 very vascular. There are no ducts in the islands of Langerhans. Their function is to furnish 

 the internal secretion of the pancreas. 



Bloodvessels, Lymphatics, and Nerves. The arteries of the pancreas come from the 

 superior pancreaticoduodenal branch of the gastroduodenal; theinferiorpancreaticoduodenal 

 branch of the superior mesenteric ; the inferior pancreatic branch of the superior mesenteric ; 

 pancreatic branches of the hepatic and pancreatic branches of the splenic. In a few cases a 

 large artery, the pancreatica magna, accompanies the pancreatic duct. In most cases there is 

 no such vessel. The veins are the anterior pancreaticoduodenal branch of the superior mes- 

 enteric; the posterior pancreaticoduodenal branch and other pancreatic branches of the 



Interlobulnr duct. 



Intralobular 

 duct. 



FIG. 1085. Section of human pancreas, showing pancreatic islands. (Radasch.) 



portal; and pancreatic branches of the splenic. The lymphatics arise in a network about the 

 lobules. Numerous collecting trunks pass to the surface of the pancreas, anastomose with each 

 other, and enter into nodes about the pancreas. The splenic nodes receive most of the trunks. 

 Others are received by nodes along the aorta (Sappey), nodes at the origin of the superior 

 mesenteric artery, and nodes along the pancreaticoduodenal vessels. The nerves come from 

 the coeliac, superior mesenteric, and splenic plexuses. 



The Pancreatic Juice. The pancreatic juice is a clear, somewhat viscid alkaline liquid. 

 Its specific gravity is about 1.030. The solid matter consists chiefly of proteids, and amounts 

 to about 10 per cent, of a sample of the juice. The juice contains a ferment which breaks up 

 tat a ferment which converts starch into sugar, and a ferment which digests proteid material. 



Surface Form. The pan<*reaTlrcs-1frfront of the second lumbaT^erteKraT-aTid can s<3me- 

 times be felt, in emaciated subjects, when the stomach and colon are empty, by making deep 

 pressure in the middle line about three inches above the umbilicus. 



Applied Anatomy Of late years our knowledge of the structure, functions, and diseases 



the pancreas has been notably increased, and surgeons have begun to operate for certain pan- 

 reatic diseases. It is occasionally the seat of cancer, which usually affects the head or duodenal 

 end, and therefore often speedily involves the common bile duct, leading to persistent jaundice. 

 Cancer of the pancreas may be primary or secondary. Primary sarcoma is very unusual; sec- 

 ondary sarcoma is more common, but cancer is far commoner than either form of sarcoma. 

 Adenoma, may also occur. Cases are on record of the successful removal of tumors of the pan- 

 creas, but the operations are very dangerous, are extremely difficult, and are seldom attempted. 

 Ihe pancreas may be the seat of syphilitic or tuberculous disease. As a result of pancreatic 

 mj ury , there may be effusion into the lesser peritoneal cavity. The lesser cavity becomes distended, 



