492 DIGESTION 



the sphincter before it has begun to disappear from the antrum with the 

 result that for a short period the antrum and sphincter together are in 

 the contracted state. Soon after this, the antrum enters upon its neg- 

 ative phase (relaxation) the sphincter being still contracted. These 

 facts are shown in Fig. 158. Fluoroscopic examination of the movements 

 of the human stomach showed that some chyme escaped through the 

 sphincter during the passage of every peristaltic wave over the antrum. 

 On the other hand the reaction of the contents of the stomach or duo- 

 denum did not have any influence on the emptying. When, for exam- 

 ple, tenth-normal hydrochloric acid was poured through a tube into the 

 antrum, in sufficient quantity to render its contents distinctly acid, no 

 effect upon the sphincter movements or their relation to the antral waves 

 could be demonstrated. One to five per cent sodium bicarbonate solu- 

 tions likewise were without effect upon the opening of the sphincter. 



Fig. 158. Tracings showing the relationship between contractions of the antrum (lower tracing) 

 and the pyloric sphincter (upper tracing). Note that the antrum precedes the sphincter but 

 that the latter contracts before the antrum has relaxed. (From Wheelon and Thomas.) 



Acids introduced through a tube into the duodenum in quantities suf- 

 ficient to render the chyme in this situation of an H-ion concentration 

 considerably in excess of that normally present was unable to prevent 

 relaxation of the sphincter in response to an antral wave. Alkaline 

 solutions in the same region failed to produce sphincter relaxation. The 

 various foodstuffs, carbohydrates, proteins and fats took approximately 

 the same time to leave the stomach, and each type of food commenced 

 to pass through the pyloric opening within a few minutes (3-12) after 

 its ingestion. (McClure, Reynolds and Swartz. 34 ) 



The foregoing account of the movements of the antrum and pyloric 

 sphincter indicates that the "law of the intestine" (page 501) with some 

 minor modifications, directs the activities of these portions of the stom- 

 ach. The experiments also appear to establish definitely the paramount 

 importance of the movements of these regions as a factor in gastric 



