Digestion
As food moves through your body (in the alimentary canal), it is gradually digested, and the valuable nutrients are extracted into your bloodstream.  Most of the absorption of nutrients occurs in the small bowel, or small intestine.  The small bowel receives the food after it is dissolved and mixed with stomach juices in the stomach.

By the time the food moves from the small bowel into the large bowel, it is mostly digested.  This remaining undigested food -- or faecal matter -- moves slowly through the large bowel until cleared.  Typically, three or four 'mass-movements' of faecal matter occur each day, triggering the urge to defecate.