How bowel works and bowel cancer

Source: http://www.cancerhelp.org.uk/help/default.asp?page=2805
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The bowel is part of the digestive system. Your doctor may call this the gastrointestinal tract, or GI tract for short. The digestive system processes all the food we eat and helps to turn it into energy and nutrients that the body can use. It also gets rid of any solid waste matter from the body.

The bowel is divided into the

(1) Small bowel or small intestine

(2) Large bowel or colon and rectum

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The small bowel is actually the longest part of the bowel - about 20 feet long. The large bowel is about 5 feet long. The small bowel is called 'small' because it is much narrower than the large bowel. When people talk about bowel cancer, they nearly always mean cancer of the large bowel. Cancer of the small bowel does happen, but it is much, much rarer.

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After food has been swallowed, it passes down the gullet or foodpipe (oesophagus) into the stomach. The food is digested and passes into the small bowel. Here digestion continues and the body absorbs the goodness (nutrients) from the foods.

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The large bowel absorbs water as the digested food passes through and the waste matter or stool gradually forms. The stool is stored in the rectum, or back passage, until it is ready to be passed out of the body as a bowel motion. The large bowel has 5 sections. Cancer can develop in any of these. They are the:

Ascending colon - the first section that runs from the appendix at the end of the small bowel up the right side of the abdomen

Transverse colon - goes across the body, under the stomach from right to left

Descending colon - goes down the left side of the abdomen

Sigmoid colon - an 's' shape bend that joins the descending colon to the rectum

Rectum - the back passage which joins the bowel to its opening on the outside, the anus

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The bowel has walls that are made up of several layers of body tissues. Bowel cancers start in the innermost layer - the lining of the bowel. If left untreated, they can grow into the muscle layers under the lining and then right through the bowel wall. It is the stage of your cancer that tells you how far your bowel cancer has grown into the wall of the bowel.

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We (cancerhelp.org.uk) think most bowel cancers take 5 to 10 years to develop. Most begin as a small growth on the bowel wall called a polyp or adenoma. Sometimes bowel cancer spreads to another part of the body.

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For more information, please visit http://www.cancerhelp.org.uk/help/default.asp?page=2805