n.
or bowel movement
Elimination of feces from the digestive tract.
Peristalsis moves feces through the colon to the rectum , where they stimulate the urge to defecate. The rectum shortens, pushing the feces into the anal canal , where internal and external sphincters allow them to be passed or retained. Chest, abdominal, and pelvic muscles are used to pass them. Long delay of defecation causes constipation and hardened feces. See also diarrhea , incontinence .