NUTRITION 



371 



tion of the food particles by the churning motion of its muscular 

 walls. The walls are also provided with millions of simple glands 

 which secrete the gastric fluid at the rate of five to ten quarts per 

 day. 



Gastric Fluid. This gastric fluid contains hydrochloric acid and 

 two ferments, rennin and pepsin. The rennin acts on the casein 

 (milk proteid) changing it to curd, 

 in which form it is more easily 

 digested by other ferments. 



(Note: rennin is used to " start " 

 cheese and in " junket tablets," the 

 latter made from calves' stomachs.) 



Pepsin, acting only in the presence 

 of an acid, changes some proteids to 

 soluble peptones and also dissolves 

 much connective tissue, thus ex- 

 posing a greatly increased food sur- 

 face for digestion in the intestine. 

 Do not get the idea, that all or even 



a great deal of proteid food is com- glan ?, s ma H n soi ^ ac ; a ' 



mouth of gland leading into a long 



pletely digested in the stomach; in w id e duct, ft, into which open the 

 fact, as fast as they are finely terminal divisions; c, connective 

 divided, many proteids are dis- 

 charged into the intestine where the 

 pancreatic fluid completes the major part of proteid digestion. 

 The stomach, then, performs four functions, namely: 



1. It acts as a storage for food. 



2. It mechanically divides and separates food particles. 



3. Rennin curdles casein. 



4. Pepsin acts on some proteid and connective tissue. 



Thus it is apparent that " stomach trouble " and digestive 

 trouble may not mean the same thing, and despite the common 

 idea, the bulk of digestive processes do not take place in the 

 stomach but in the small intestine. 



The food as it is discharged into the intestine is called chyme 

 and consists of 



FIG. 119. Section of pyloric 



After Piersoe. 



tissue of mucosa. 

 See Kellogg. 



