CHAPTER VIII 

 DIGESTION IN THE STOMACH 



Importance. When the food has been mixed with the saliva 

 and ground into small pieces by the teeth it is swallowed, and 

 passed down the esophagus into the stomach. The stomach is 

 a muscular, strong walled organ, which is collapsed or con- 

 tracted upon itself when empty, but is capable of being greatly 

 distended. If water is taken alone, it quickly runs through the 

 stomach into the intestine, but solid food collects in a more or 

 less solid mass near the entrance. It remains in the stomach 

 for a considerable time, (1-5 hours) passing on little by little 

 as it is thoroughly mixed with the gastric juice. The stomach 

 thus serves primarily as a reservoir into which considerable 

 amounts of food may be taken at a time. Since its walls are 

 strong and muscular they are in no danger of being ruptured. 

 The stomach thus stands between the more delicately constructed 

 intestine and the mass of food taken in a normal meal, and 

 passes along the food material in small amounts so as not to 

 overtax the capacity of the intestine. However, the stomach 

 also fulfils important digestive functions. 



Methods of Study. The digestive functions of the stomach 

 are due to constituents of a juice secreted by numerous small 

 glands scattered in the stomach wall. The study of this 

 juice and its activities has received the attention of scientific 

 men for a very long time. One of the chief difficulties was the 

 manner of obtaining juice for study. Spallanzani, working in 

 the latter part of the eighteenth century, swallowed food tied 

 up in small linen bags which ultimately were passed with the 

 f eces. By studying the residues in the bags, the effects of diges- 

 tion on the food could be observed. Another method consisted in 

 swallowing a sponge tied to a string. The sponge soaked up 



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