THE PANCREAS AND THE LIVER 117 



such as glucose, they will not be. In any case, 

 enzymes secreted by the sail vary, pancreatic and 

 intestinal glands and sent into the digestive tract, 

 are ever ready to convert complex into simple 

 carbohydrates. The chemically simple carbo- 

 hydrates, of which there are three well-known 

 types (glucose, levulose, galactose), are absorbed 

 by the blood, sent to the liver and there stored in 

 the form of glycogen or "animal starch." 



Glycogen. Chemically, glycogen is about as 

 complex as starch. If, therefore, the simple carbo- 

 hydrates, obtained from starch and similar bodies 

 by the breaking up of the starch molecule, are con- 

 verted in the liver into glycogen, it can mean but 

 one thing: that there must be a recombination of 

 the simple carbohydrate molecules to form gly- 

 cogen. 



But this is not all. Whenever the body needs 

 carbohydrate which it does much of the time for 

 its energy supply it calls on this glycogen stored 

 in the liver. The glycogen is first converted back 

 again into a simple sugar but one only namely 

 glucose, and this glucose is sent via the blood to the 

 various muscles, where it is "burnt" to supply the 

 fuel needs of the body. 



Summarizing then the glycogen function of the 

 liver, we may say that the carbohydrates we eat, 

 after an appropriate preliminary simplification in 

 the digestive tract, are transferred to the liver by 



