The Endocrine System 237 



In recent years there has been tremendous interest in the use of 

 cortical extracts for the alleviation of the symptoms of arthritis and 

 rheumatism. These drugs must be used with caution, for the ac- 

 companying secondary effects may prove to be undesirable. 



THE PANCREAS 



Just behind and slightly below the stomach is a pink, lobulated 

 organ, the pancreas. A thin layer of connective tissue covers this large 

 diffuse gland. Leading from it are one or two ducts which enter the 

 duodenum of the small intestine. 



Microscopic examination of this gland reveals the fact that there 

 are two distinct types of cells present. The greater portion of the 

 pancreas is formed of groups of epithelial cells which are arranged 

 around the terminations of ducts which ultimately fuse to form the 

 pancreatic duct or ducts leading to the duodenum. These cells form the 

 exocrine portion of the gland, that is, the portion that elaborates the pan- 

 creatic juice, one of the important digestive secretions. Scattered 

 throughout this main mass of epithelial cells are clusters of cells which 

 stain differently and are richly supplied with blood. These are the 

 islets of Langcrhans, the endocrine portion of the pancreas. These 

 islets secrete the important hormone, insulin. Thus the pancreas is 

 a double gland having two distinct functions : one is the production of 

 the digestive secretion, the other is the elaboration of the hormone. 



The Function of the Islets of Langerhans. — The insulin se- 

 creted by the islets of Langerhans is but one of many factors important 

 in the proper usage of carbohydrates. Its role seems to be that of 

 making possible the oxidation and storage of the simple sugars. The 

 exact manner in which the simple sugars are utilized is not entirely 

 clear, but some slight understanding of this complexity is possible. 



During the discussion of carbohydrates it was pointed out that the 

 starches and sugars were changed by the digestive enzymes into the 

 monosaccharides bearing the general formula CeHioOe. These are 

 soluble forms which are able to go from the intestine into the blood 

 and thus become available for energy. The sugars, when absorbed by 

 the blood, may be utilized immediately for energy, or they may be 

 stored by the liver in the form of glycogen. This glycogen then is re- 

 converted into glucose and released back into the circulation as it is 

 needed by the body. These changes are mediated through a series of 



