BILE 77 



Absorption of Carbohydrates. — Though the sugar formed from 

 starch by ptyalin and amylopsin is maltose, that found in the blood is 

 glucose. Under normal circumstances little if any is absorbed by the 

 lacteals. The glucose is formed from the maltose by the succus 

 entericus, and perhaps also by the vital action of the epithelial cells. 

 Cane sugar and milk sugar are also converted into glucose before 

 absorption. 



The carbohydrate food which enters the blood as glucose is taken 

 to the liver, and there stored up in the form of glycogen— a reserve 

 store of carbohydrate material for the future needs of the body. 

 Glycogen, however, is found in animals which take no carbohydrate 

 food. It must, then, be formed by the protoplasmic activity of the 

 liver cells from their proteid constituents. The carbohydrate store 

 leaves the liver in the blood of the hepatic vein as glucose (dextrose) 

 once more. 



The above is a brief statement of the glycogenic functions of the 

 liver as taught by Claude Bernard, and accepted by the majority of 

 physiologists. It has always been strongly contested by Dr. Pavy, 

 who has in a recently pubhshed book revived the question. Dr. 

 Pavy's theory is that the glycogen formed in the liver from the sugar 

 of the portal blood is never during life reconverted into sugar, but is 

 used in the formation of other substances like fat and proteid ; in sup- 

 port of this he has shown that proteids contain a carbohydrate radicle. 

 He denies that the post-mortem formation of sugar from glycogen that 

 occurs in an excised hver is a true picture of what occurs during life. 



Absorption of Proteids. — A certain amount of soluble proteid is 

 absorbed unchanged. Thus, after taking a large number of eggs, 

 egg albumin is found in the urine. Patients fed per rectum derive 

 nourishment from proteid food, though proteolytic ferments are not 

 present in this part of the intestine. 



Most proteid, however, is normally absorbed as peptone and 

 proteose (albumose). Peptones and proteoses are absent from the 

 blood under all circumstances, even from the portal blood during the 

 most active digestion. In other words, during absorption the 

 epitheUal cells change the products of proteolysis (peptones and 

 proteoses) back once more into native proteids (albumin and 

 globulin). 



The greater part of the proteid absorbed passes into the blood ; a 

 little into the lymph vessels also ; but this undergoes the same change. 



When peptone (using the word to include the proteoses also) is 

 injected into the blood stream, poisonous effects are produced, the 

 coagulability of the blood is lessened, the blood pressure falls. 



