The Digestion of Food 



121 



is shown by the fact that certain poisonous chemicals, like 

 cyanide of potash, if kept in the mouth for a few moments, 

 will cause death. While we are chewing and swallowing 

 our food, no doubt a certain amount of water and common 

 salt, together with sugar which has been changed from 

 starch by the action of the saliva, gains entrance to the 



blood - pn^ 



In the stomach, however, absorption takes place 



great-activity. The semiliquid food is separated from the 

 enormous supply of blood vessels in the mucous membrane 



FIG. 59. Diagrammatic Scheme of Intestinal Absorption. 



A, mesentery ; B, lacteals and mesentery glands ; C, veins of intestines ; R. C. } 

 receptacle of the chyle (receptaculum chyli) ; P. V., portal vein ; H. K, hepa- 

 tic veins ; S. V. C., superior vena cava ; R. A., right auricle of the heart ; 

 /. V. C., inferior vena cava. 



only by a thin porous partition. Water, along with any 

 substances in the food that have become dissolved, will 

 pass through this partition and enter the blood current. 

 A certain amount of starch that has been changed into 

 sugar, of salts in solution, of proteids converted into pep- 

 tones, is also taken up directly by the blood vessels of 

 the stomach. 



/ 184. Absorption by the Intestines. The greatest part of 

 absorption is accomplished by the small intestines. They 



