THE METABOLISM OF CARBOHYDRATE 



431 



breaking down of dextrose by the muscles. The parts possibly played 

 by the secretions of the suprarenal and pancreas are shown diagram- 

 matically in Fig. 218. 



Glycosuria. Dextrose may appear in the urine under any of the 

 following conditions: 



1. The liver, supplied with too much dextrose, is unable to deal 

 with it all, so that an excess of sugar passes into the blood and is 

 excreted by the kidneys. 



2. The liver, over-stimulated, suddenly turns a large amount of 

 glycogen into dextrose, floods the blood with sugar, and thus induces 

 glycosuria. 



3. The glycogenic function of the liver remains normal, but the 

 power of the body to break down dextrose is diminished, so that the 

 sugar accumulates in the blood, and this leads to glycosuria. 



(Sugar Content) 

 Blood 



Pancreas Secretion. 



Liver. 

 (Glycogen Store) 



FIG. 218. DIAGRAM INDICATING INFLUENCE OF PANCREAS AND SUPRARENALS ON 

 CARBOHYDRATE METABOLISM. (After Underbill and Fine.) 



4. There is no excess of dextrose in the blood, but sugar forms 

 within the kidney substance itself, and is excreted in the urine. 



5. The amount of dextrose in the blood remains normal, but the 

 kidneys become more " permeable " to sugar. Thus sugar, which is 

 normally retained in the body, passes into the urine. 



When glycosuria occurs, it may be due to one or other or a 

 combination of these conditions. Glycosuria may be experimentally 

 induced in various ways, the chief of which are the following : 



1. Alimentary Glycosuria. This follows the ingestion of too much 

 sugar for example, 150 to 200 grammes of dextrose, and considerably 

 less lactose, levulose, and galactose. Children sometimes eat J pound 

 or even pound of sweets. Alimentary glycosuria is due to the 

 " flooding " of the liver with too much sugar. It is sometimes termed 

 " glycosuria e saccharo." It may also be produced, but more rarely, 



