REFLEX PERISTALSIS OF THE INTESTINE

Abstract

In the duodenum of the dog the introduction of a bolus strongly increases the strength of the rhythmic contractions on the oral side, with little or no effect caudally. This activity differs from spontaneous contractions only by their greater strength and participation of the circular muscles. In strong peristalsis a single powerful and prolonged contraction sweeps over the intestine. The latter type of response is seen frequently in the rectum of the rabbit and terminal ileum of the dog, less often in the duodenum of the dog. Since all gradations between these responses can be observed, the prolonged contractions may be considered as the result of a fusion between several rhythmic contractions. This view is confirmed by a study of action potentials which differ usually from ordinary rhythmic contractions only by the greater strength of the spike discharge. However, in the ileum of the dog, no regular action potentials were observed during the strongest peristaltic waves, indicating a prolonged and continuous state of activity.