ABSORl'THLX OF FOOD CONSTITUENTS 



333 



vein and discharge into the liver. Jn the liver the carbo- 

 hydrates are changed into glycogen until such time as 

 dextrose is needed in the blood, when the glycogen is trans- 

 formed into dextrose. Enzymes in the liver accomplish the 

 dehydration change to glycogen as well as the hydrolytic 

 change to dextrose. 



Vein 



Artery 



Central lacteal 



Fig. 81. — Diagrammatic section through villi of small intestine. 



Bohm and Davidoff, after Mall.) 



(From 



Fats are probably absorbed as glycerine and soaps, 

 although possibly also in the form of emulsified fats, and pass 

 through these outer cells of the villi into the lymph vessels or 

 lacteals. During the process of this absorption the glycerine 

 unites with the fatty acids of the soaps to form fats, so that 

 the lymph as it leaves the villi is charged with liquid globules 

 of fat to such an extent as to give it the appearance of milk. 

 The lymph vessels join the thoracic duct from which the 

 fatty particles are discharged into the veins and thus get 

 into the general circulatory svstem of the blood. 



The proteins in the form of peptones or possibly amino- 

 acids are absorbed into the blood-vessels of the villi, during 

 which process they combine to form the serum-albumin 



