Functional disorders are those in which the gastrointestinal (GI) tract looks normal but doesn't work properly. They are the most common problems affecting the GI tract (including the colon and rectum). Constipation and irritable bowel syndrome (IBS) are two common examples. Functional Gastrointestinal Disorders Many factors may upset the GI tract and its motility (or ability to keep moving), including: Eating a diet low in fiber Not enough exercise Traveling or other changes in routine Eating large amounts of dairy products Stress Resisting the urge to have a bowel movement Resisting the urge to have bowel movements due to pain from hemorrhoids Overusing laxatives (stool softeners) that, over time, weaken the bowel muscles Taking antacid medicines containing calcium or aluminum Taking certain medicines (especially antidepressants, iron pills, and strong pain medicines such as narcotics) Pregnancy Constipation: Constipation means it is hard to have a bowel...