Relaxations of the Internal Anal Sphincter Elicited by Rectal and Extrarectal Distensions in Man
The high pressure zone of the anal canal is mainly dependant at rest on the activity of the internal anal sphincter (IAS). This sphincter is reflexly relaxed when the rectal wall is distented. This phenomenon provoked by the stimulation of stretch receptors occurs in defecation or in experimental conditions after inflation of a balloon in the lumen. Such experimental distension is also effective in sigmoid (1). The present study was designed to investigate the responses obtained after distension of different parts of the lower digestive tract and to compare them to the response after rectal stimulation. It was attempted to define place of these reflex activities during defecation and among mechanisms of continence.
KeywordsAnal Canal Gastrointestinal Motility External Anal Sphincter Internal Anal Sphincter Reflex Activity
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