390 



ABSORPTION 



but are readily absorbed when the more concentrated solutions are intro- 

 duced into the stomach, 5 per cent, and over (von Mehring). Fats are not 

 absorbed at all in the stomach. Even salts in the stomach are not readily 

 absorbed until the concentration is from three to four times that of the 

 blood. This fact is in direct opposition to the popular views on the subject. 



While some absorption does take place in the stomach it is evidently not 

 of any great importance under normal conditions. The presence of alcohol 

 has been shown to increase the amount of absorption, and pepper, mustard, 

 and such drugs as produce mild local irritation accomplish the same result. 



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

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







FIG. 279. Scheme of Blood Vessels and Lymphatics of Human Small Intestine, a, 

 Central lacteal of villus; b, lacteal; c, stroma; d, muscularis mucosse; e, submucosa;/, plexus 

 of lymph vessels; g, circular muscle layer; h, plexus of lymph vessels; i, longitudinal 

 muscle layer; j, serous coat; k, vein; /, artery; m, base of villus; n, crypt; o, artery of villus; 

 p, vein of villus; q, epithelium. (Mall.) 



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 



