494 DIGESTION 



of the duodenum occurs a short time after the commencement of the 

 sphincter contraction. Superimposed upon the duodenal peristaltic 

 waves are rhythmical segmentary movements (A, B, C, D, E) . The first 

 of these occurs at the commencement of the peristaltic wave and coin- 

 cidently with the maximal height of the sphincter contraction. The sec- 

 ond segmentary wave surmounts the crest of the peristaltic wave in the 

 duodenum and occurs during relaxation of the sphincter. 



The peristaltic waves in the duodenum by the withdrawal of material 

 from the " reservoir cap" will aid in the evacuation of the latter. This 

 receives the chyme during the contraction of the antrum but none can 

 return to the antrum when this relaxes since now the sphincter is closed. 

 The motility of the stomach appears to influence duodenal peristalsis 

 and in this way indirectly aids in the withdrawal of material from the 

 ''cap" which it is the purpose of the antral and sphincter activities to 

 fill. On the other hand duodenal motility influences the activity of the 

 sphincter for stimulation of the duodenum below the "cap" in addi- 

 tion to a contraction at the stimulated point and relaxation below, pro- 

 duces a sharp contraction of the sphincter followed by a prolonged nega- 

 tive phase. Sphincter motility unassociated with antral activity may in 

 this way be induced. From these considerations it may be seen that the 

 peristaltic waves in the duodenum which hasten the emptying of the 

 cap by the withdrawal of its contents are probably, through their influ- 

 ence upon the sphincter, a factor also in the filling of the "cap" from 

 the stomach side. That the degree of receptivity of the duodenum is an 

 important factor in emptying the cap is indicated by the observation that 

 a dog starved for 18 hours emptied its stomach of an 8 oz. barium meal 

 in 80 minutes while a second meal of the same amount was not entirely 

 removed after 2% hours. 



Influence of Pathological Conditions on the Emptying 



An important surgical application of these facts concerns the behavior 

 of food after gastroenterostomy. It has been thought that this operation 

 would cause the food to be drained from the stomach into the intestine 

 and thus leave the region of the stomach between the fistula and the 

 pylorus inactive. This assumption is based on the idea, which we have 

 seen to be erroneous, that gravity assists in the emptying of the stomach. 

 As a matter of fact, it has been found that, if the gastroenterostomy is 

 fnade when there is no obstruction at the pylorus, the chyme takes its 

 Aiormal passage through the sphincter and, almost without exception, 

 '/none leaves by the fistula. When the pylorus is partly occluded, the 

 food sometimes passes in the usual way, and sometimes by the fistula. 

 The cause for this predilection for the pyloric pathway depends on the 



