iia 



DIGESTION 



It also tends to kill bacteria and prevent fermentation and aids in 

 the solution of certain mineral salts. 



3. The pepsin converts proteid into soluble peptone, part of 

 which is absorbed directly by the blood vessels of the stomach. 



4. The rennin coagulates the proteid in milk and prepares it for 

 the action of the pepsin. 



5. The partly digested proteids, and starch together with the 

 undigested matter leaves the stomach as an acid mixture called 

 chyme. 



Digestion in the Intestine. 



While some starch is changed 

 to sugar in the mouth and some 

 proteid to peptone in the stom- 

 ach, the real seat of digestion 

 in the body is the small intes- 

 tine. Here all kinds of nutri- 

 ents are digested, and the final 

 preparation of the food for use 

 in the body takes place. Here, 

 too, the digestible- matter is 

 separated from the indiges- 

 tible. In short, even if there 

 were no preliminary mouth or 

 stomach action, the small in- 

 testine would be capable of 

 performing all the digestive 

 actions necessary to prepare 

 the food for the body. 



The intestine. — All of the 



alimentary canal between the 



stomach and the anus is 



known as the intestine. This 



of a tube of varying diameter, 



Fig. 39 — The stomacli and intes- 

 tiues ; 1, stomacli ; 2, duodenum ; 

 3, small intestine ; 4, end of 

 ileum ; 5, Ciecum ; 6, vermiform 

 appendix ; 7, ascending colon ; 

 8, transverse colon ; 9, descend- 

 ing colon ; 10, sigmoid flexure ; 

 11, rectum ; 12, anus. 



part of the canal consists 



