Chronic disorder characterized by abdominal pain, intestinal gas, and diarrhea, constipation, or both. Other symptoms may include abdominal pain that is relieved after defecation or a sensation of incomplete rectal evacuation. IBS is caused by a motility disturbance of the intestines that may result from increased intestinal sensitivity to distension. Stress or the consumption of fatty foods, milk products, certain fruits or vegetables (e.g., broccoli and cabbage), alcohol, or caffeine may cause similar symptoms. Treatment includes relaxation, exercise, and avoidance of aggravating foods. Antidiarrheal medications or fibre supplements may help lessen symptoms. Although IBS may cause discomfort and emotional distress, the disorder does not result in any permanent intestinal damage.
Learn more about irritable bowel syndrome with a free trial on Britannica.com.
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. Seealso diarrhea, incontinence.
Learn more about defecation with a free trial on Britannica.com.