THE PROTEINS AND THEIR METABOLISM 



103 



Schematic Illustration of the Digestion of Proteins in the Gastro- 

 intestinal Canal 



.PROTEIN. 



"Metaprotein. Proteosc. 



I I 



Pioteose. Proteose. 



Proteosc. 



Dipeptids. 



Peptones. 



Peptones. Polvpeptids. 



I 'I 



Polypeptids. Dipeptids. 



Amino-acids. 



Ammo-acids. 



Prolin. 

 Phenylalanin, etc. 



Peptone. 



I 



Polvpeptids. 



"I. 



Dipeptids. 



.1 



Amino-acids. 

 Tyrosin. 

 Tryptopban. 

 Cystin. 

 Leucin. 



Pepsin-HCl diges- 

 tion in the 

 stomach. 



Trypsin diges- 

 tion in the in- 

 testines. 



Erepsin. diges- 

 tion. 



The above shows in a general way the scheme of protein digestion, and 

 is reproduced to show that the protein molecule does not break up in an 

 explosive manner, by which the whole molecule disintegrates, but that it 

 i;ikcs place in stages, and that a large number of intermediary bodies are 

 possible in the course of protein digestion. 



The Absorption of Products of Protein Digestion 

 from the Gastro-Intestinal Canal 



From what, was said above it is evident that digestion in the stomach 

 <!<><'s not proceed to the point where products are formed that are ab- 

 rluible. Hence very little or no absorption of protein-digestion-products 

 t;ikes place normally ( London- Abderhal den). If amino acids or peptones 

 j're introduced into the stomach they are absorbed with considerable rapid- 

 ity (Folin and Lyman, 1012 (a)). 



The greatest bulk of the absorption takes place from the intestines, 

 Irom which the lower peptids and amino acids are absorbed with great 

 !;ij>i<lity, and carried by the blood stream to the various organs of the 

 Univ. 



