FOOD AND DIGESTION 353 



or in part, as when an artery is occluded or ligatured, the dead 

 part is digested by the gastric juice and the wall of the stomach 

 may be perforated. In the living condition a substance may 

 be extracted from the mucous membrane which antogonises 

 the action of pepsin and may be called antipepsin. 



(d) Antiseptic Action of the Gastric Juice. In virtue of the 

 presence of free HC1 the gastric juice has a marked action in 

 inhibiting the growth of or -in killing bacteria. The bacillus 

 of cholera is peculiarly susceptible, and a healthy condition of 

 the stomach is thus a great safeguard against the disease. 

 Other organisms, while they do not multiply in the stomach, 

 pass on alive to the intestine where they may again become 

 active. When HC1 is not formed in sufficient quantities to 

 exist free in the stomach, the activity of these bacteria in the 

 organ may lead to various decompositions and to many of the 

 symptoms of dyspepsia. 



(e) Source of the Constituents of the Gastric Juice. The 



hydrochloric acid is formed at the cardiac end of the stomach. 

 This may be shown by isolating a part of the stomach so that 

 it opens on the surface. Since the parietal or oxyntic cells 

 are confined to this portion of the stomach, it may be concluded 

 that they are the producers of the acid. They manufacture 

 it from the NaCl of the blood plasma. Probably the C0 2 

 liberated in the cells seizes on some of the Na and turns 

 out HC1. 



The Pepsin and Rennin are produced in the chief or peptic 

 cells which line the glands both of the cardiac and pyloric 

 parts of the stomach. During fasting granules are seen to 

 accumulate in these cells, and when the stomach is active 

 they are discharged. These granules are not pepsin but the 

 forerunner of pepsin pepsinogen. 



(/) Influence of Various Diets upon the Gastric Juice. This 

 has been chiefly worked out by Pavlov on dogs with a gastric 

 pouch (p. 349). 



He finds that (1) The amount of secretion depends upon 

 the amount of food taken. (2) The amount and course of 

 secretion varies with the kind of food taken. Thus, with 

 flesh the secretion reaches its maximum at the end of one 



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