Large intestine

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Large intestine
Front of abdomen, showing the large intestine, with the stomach and small intestine in dashed outline.
Front of abdomen, showing surface markings for liver (red), and the stomach and large intestine (blue).
Latin intestinum crassum
Gray's subject #249 1177
Lymph inferior mesenteric lymph nodes
Dorlands/Elsevier i_11/12456545

The large intestine, or the organ which is now more commonly referred to as the colon, is the last part of the digestive system: the final stage of the alimentary canal in vertebrate animals. Its function is to absorb the remaining water from indigestible food stuffs, stores these unusable food stuffs (wastes) and then eliminates the wastes from the body.

The large intestine starts in the right iliac region of the pelvis, just at or below the right waist. Joined to the bottom end of the small intestine, it consists of the cecum, colon, rectum and anal canal. The large intestine is about 1.5 metres long, which is about one-fifth of the whole length of the intestinal canal.

Contents

[edit] Function and relation to other organs

The large intestine takes 12 to 24 hours to finish up the remaining processes of the digestive system. Food is not broken down any further in this stage of digestion. The large intestine absorbs vitamins that are created by the bacteria. It also absorbs water. Despite this the large intestines main function is not that of absorption. Its main job is elimination of feces. The large intestine, if necessary, can be removed and is not necessary for life.

The most obvious difference between the small intestine and the large intestine is that the large intestine is wider. The wall of the large intestine differs from that of the small intestine. It is simple columnar epithelium.It lacks villi (the majority of food is absorbed in the small intestine). Mucosa is thicker, crypts are deeper and it has a large number of goblet cells.

The vermiform appendix is attached to its posteromedial surface of the large intestine. It contains masses of lymphoid tissue. It is a part of MALT which gives the appendix an important role in immunity. Appendicitis is the result of a blockage that traps infectious material in the lumen.

[edit] Bacterial Flora

Houses over 700 species of bacterial flora. They preform a variety of functions in the large intestine. Among the many jobs are synthesis of vitamin B complex vitamins and vitamin K. There are at least 20 known pathogenic micro-organisms living in the intestine.

[edit] Parts and location

Parts of the large intestine are:

  • ceccum - the first part of the large intestine
  • vermiform appendix - mass of lymphoid tissue
  • haustrum - pocket like sacs
  • epiploic appendages - small fat filled pouches of visceral peritoneum that hang from the surface
  • teniae coli - three bands of smooth muscle
  • rectum
  • anal canal - last segment of the large intestine
  • external anal sphincter

Locations along the colon are:

  • The ascending colon
  • The right colic (hepatic) flexure
  • The transverse colon
  • The transverse mesocolon
  • The left colic (splenic)flexure
  • The descending colon
  • The sigmoid colon - the s shaped region of the large intestine


[edit] Additional images

[edit] External links

Look up Large intestine in
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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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