GASTRIC DIGESTION 



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II. GASTRIC JUICE AND GASTRIC DIGESTION. 



9. The Secretion of Gastric Juice. The conditions which influence 

 gastric secretion can be readily observed on the dog with a gastric fistula. 

 Take a dog which has had a gastric fistula prepared some weeks before and 

 which is in a condition of hunger, place him in a holder with a cup suspended 

 to collect the gastric juice, and exhibit before the dog some fresh meat or 

 other food which he enjoys, but do not allow him to eat it. After teasing the 

 animal for 5 or 10 minutes, an abundant flow of gastric juice will begin. Paw- 

 low calls this the psychic secretion. 



If an esophageal fistula has also been performed on the animal the dog 

 may be allowed to eat the meat, of course swallowing it out of the esophageal 



FIG. 278. Operation on the Stomach to Form an Isolated Pouch with Nerves Intact. S, 

 Isolated sac; V, cavity of stomach; A, A, opening at the abdominal wall. 



fistula back into the- plate. In this experiment an abundant flow of gastric 

 secretion takes place and may continue for an hour or more. 



If a gastric pouch has been performed by Pawlow's method, the animal 

 may be allowed to eat the food, swallowing it into the stomach. In this case 

 the reflex secretion just described takes place as usual, but is followed after 

 an hour or an hour and a half by a second increase in the quantity of secretion. 

 This second increase has been ascribed to the reflexes originating in the 

 stomach, possibly from the reflex stimulating action of the digestive products 

 themselves. 



10. Composition of Gastric Juice. Test a sample of gastric juice 

 obtained from a gastric fistula, as follows: 



Reaction. Gastric juice is strongly acid. Test for free hydrochloric acid 



