MOVEMENTS OF THE STOMACH 



329 



softened layers of food by propelling it into the pylorus. There it is thoroughly 

 mixed with the gastric juice, forming the chyme. Figure 261 gives an idea of 

 the movement of the food in the antrum. The peristaltic contractions carry 

 it forward, but if the valve does not open to permit passage to the duodenum, 

 then the pressure will force the chyme back through the center toward the 

 fundus. After several minutes the pyloric sphincter will occasionally relax 

 to allow fluid food to pass to the duodenum, but when more solid particles come 



11A.M. 



12M. 



2RM, 



5P.M. 



FIG. 262. Outlines of the Roentgen-ray Shadows of the Stomach Content as Digestion 



(Cannon.) 



up against the valve the sphincter promptly contracts and remains so for some 

 time. Toward the completion of digestion even solid undigested particles are 

 carried on into the intestine. 



The movements of the stomach are under nervous regulation. Cannon 

 found that the peristalses were promptly inhibited in cats by excitement. Stim- 

 ulation of the vagi leads to contractions of the stomach, w r hile the splanchnics 



