Large Intestine

(Large Bowel, Colon)

colon colon

User's Manual: Appendix
User's Manual: Colon
Amazing Facts
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The last 1.5 meters of the intestine. The large intestine is much broader than the small intestine and takes a more consistent, less complex path through the abdomen. By the time the chyme (food mixed with digestive juices) reaches the large intestine, most digestion and absorption has taken place. All that's left is primarily fiber (plant matter not easily digestible), dead cells shed from the lining of the gut, salt, bile pigments and water. Within the large intestine, bacteria feed on the contents. The bacteria produce valuable vitamins that are absorbed into the blood, and enzymes that further digest fibrous vegetable matter. The colon is also the principle place for water reabsorption, and absorbs salts when needed.


A 5 to 7 cm (2 to 2.8 inch) pouch in the lower right region of the abdomen that connects the ileum to the ascending colon, and helps somewhat to prevent backflow of fecal matter into the ileum. The appendix opens into the cecum as well.


A narrow, worm-shaped, lymphatic tube about 8 cm (3.1 inches) in length, which opens into the cecum of the large intestine. In the fetus the appendix contains glands that manufacture hormones and other important body chemicals. In young adults the appendix participates in the immune system, providing a place in which white blood cells mature, and in which antibodies are produced.

User's Manual: Appendix

An infection of the appendix, most common between ages 15 and 24. It's usually caused by a blockage of the large intestine, commonly resulting from a fiber-deficient diet. The blockage reduces the flow of fluids, allowing bacteria to grow and to infect the appendix. Symptoms include severe abdominal pain beginning close to the navel and migrating toward the right lower abdomen. The pain is worsened by deep breaths, coughing, sneezing, moving or being touched in this area. Nausea and vomiting are common. As the illness progresses you may experience diarrhea, abdominal swelling, mild fever, constipation, an inability to pass gas, painful urination and blood in the urine. If you notice these symptoms, see your doctor. The best way to avoid appendicitis is to eat a fiber-rich diet. (See fiber under nutrition)

The major section of the large intestine, consisting of 4 parts...

  • Ascending colon: The first ascending right portion of the colon using peristaltic waves to push undigested debris upward from the cecum to a location just under the right lower end of the liver.
  • Transverse colon: The second portion of the colon, pushing its contents across the anterior abdominal wall, sweeping from left to right traveling just under the stomach.
  • Descending colon: The third portion of colon, pushing its contents from just near the spleen to the lower left side of the abdomen.
  • Sigmoid colon: The final S-shaped length of the colon, leaving the body wall, curving among the coils of small intestine, and emptying into the rectum.

User's Manual: Colon

100,000 Americans die each year from colon cancer. 15% of cancer deaths are due to this disease. It is difficult to detect and thus very deadly. To avoid it, eat your fiber. Fiber is plant matter that is not easily digestible in the gut. Examples of fiber...

  • Pectin (complex sugar found in fruit known to reduce lead poisoning)
  • Cellulose (the material that keeps plant stems rigid)
  • Lignins (another substance that contributes to a plant's skeleton or form)
  • Waxes
  • Brans
  • Germs
  • Husks
  • Natural gum

There are a number of theories as to why fiber prevents cancer of the colon. The most popular view is that fiber retains water, which softens the stools easing their passage through the large intestine. This rapid transit allows less exposure of cancer causing agents to the tissue in your gut. This also means, however, that you have less time to absorb nutrients. So while you are still growing, don't eat tons of fiber or you could cause malnutrition. Also if you do increase fiber in your diet, do it gradually. Increasing it too fast could cause gas and diarrhea. A good daily dose of fiber is 30 to 40 grams, the same dose as a typical vegetarian.

In addition to fiber-deficient diets, fat has been linked to colon cancer as well, so as usual limit your total fat intake. Fast food that's fried is bad for you.

Eat fiber foods to prevent cancer and appendicitis! Here's a list of fiber-rich foods in order of most fiber per serving to least...

serving size grams of fiber (roughly)
1 16.4
4 oz. 7.9
Boiled soybeans
4 oz. 5.0
Chick peas (found in humus)
1/2 cup 5.0
Dried figs
1/2 cup 4.8
Coconut meat
4 oz. 4.5
Dehydrated apricots
4 oz. 4.3
1/2 cup 3.4
Hulled blackberries 1/2 cup 3.0
Boiled broccoli (raw would be better) 1 stalk 2.7
Pitted dates 4 oz. 2.6
Crude bran 1 oz. 2.6
Boiled Brussels sprouts (pee yoo!) 1 cup 2.5
Dried Apricots 1 cup 2.4
Apple with skin 1 2.3
Pared parsnips 4 oz. 2.3
Pear 1 2.3
Shelled black walnuts 4 oz. 1.9
Chopped roasted peanuts 1/2 cup 1.7
Boiled green peas 1/2 cup 1.6
Boiled lima beans 1/2 cup 1.6
Cooked kidney beans 1/2 cup 1.4
Chestnuts 4 oz. 1.2
Cooked lentils 1/2 cup 1.2
Boiled turnip 1/2 cup 1.0
Whole wheat bread 2 slices .8
Whole wheat crackers 1 oz. .9
Boiled green beans 1/2 cup .6

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Amazing Facts

  • You consume 30 tons of food throughout your life.
  • It takes 24 hours to completely digest food.
  • The digestive tube from your mouth to your anus is 9 meters or 30 feet long.
  • The digestive system has a surface area of 2000 square feet.
  • The surface area of the digestive system is approximately equal to that of a single's tennis court!
  • The average person eats 3 lbs. of food daily.
  • Water molecules in the gut can move at 1500 miles/hour due to peristalsis.
  • The large intestine averages 5 feet long.
  • The colon is home to 100 trillion bacteria.
  • Human feces are normally 1/4 dead intestinal bacteria.
  • The body's bacteria could fill a soup can.
  • The bacteria as it naturally exists within the lumen (or hollow space) of the digestive tract is perfectly harmless and beneficial, helping the digestion and absorption of food that otherwise couldn't be absorbed. However, if this bacteria ever did enter the body and the blood, due to a ruptured digestive organ, it could be extremely harmful and even lethal.
  • The lumen (contents) of the digestive tract is considered outside the body like the hole of a donut, since it's continuous with the outside of the body. The lungs and kidneys eliminate most of the waste products from inside the body. The digestive tract is disqualified from this function, since most contents of feces never technically enters the body.

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Glands involved in digestion