The large bowel (colon) consists of five main parts. The ascending colon runs from the right lower quadrant to the right upper quadrant. As it crosses over to the left upper quadrant, it is called the transverse colon. The descending colon starts in the left upper quadrant making its way to the left lower quadrant. The sigmoid colon is a large floppy part of the colon that connects the descending colon to the rectum, the last part of the colon.
While absorption of nutrients mostly takes place in the small bowel, water absorption occurs in the colon. 90% of water absorption occurs in the ascending or right colon. As the water is absorbed from stool traveling through the colon, it becomes more solid in its form. Stool eventually comes to reside in the rectum where an urge to have a bowel movement is felt.
If you've had ostomy surgery, you'll no longer have the ability to control the movement of your bowels, and you'll need to wear a pouch to collect the stool.