414 ABSORPTION 



Absorption in the Intestines. The products of digestion are all readily 

 absorbed in the small intestine, as is abundantly shown by experiments. 

 Absorption from the small intestine has been studied in the human subject 

 in the case of a patient who had a fistulous opening in the lower part of the 

 ileum. For example, 85 per cent, of the protein of a test meal was absorbed 

 before the food reached the fistula. The food passes slowly down the length 

 of the small intestine, and the digestive changes produce a series of cleavages 



Lymphatics of head and I ~"' : - "'ffittHlBi^fe^:;^ '- *V^afcSl Lymphatics of head and 

 neck, right ' HlttyS&OT ' && - xfKS^ neck, left 



' 'nl'QBBtHf^ScfuiK^ 



Right internal jugular vein j S^UHHflK^^S Thoracic duct 



Right subclavian vein .___ ___ ... ,____. 



^m.* ^K** -BKB^I^^BHU* Left subclavian vein 

 Lymphatics of right arm 



Thoracic duct 



Receptaculum chyli 



Lacteals 



Lymphatics of lower ex- SVV^UHi^BYT^^] I Lymphatics of lower ex- 



tremities EnJKIvVHBHHlf'nU^avHP tremities 



FIG. 280. Diagram of the Principal Groups of Lymphatic Vessels. (From Quain.) 



which have known osmotic and diffusion properties. The question has been 

 to determine which of the cleavage products are most favorable for absorp- 

 tion and the details of the mechanism. 



The mucous membrane of the small intestine possesses special structures 

 for absorption, the villi. Each villus projects as a finger-like process into 

 the lumen of the intestine. Its single-layered covering of epithelial cells 

 supported by a connective-tissue framework brings a relatively large extent 

 of surface into contact with the digesting food, which is thus separated from 

 a loop of capillaries and lymphatic radicals. 



