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 matter, stores these unusable food matter (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.

1 Function and relation to other organs
2 Bacterial Flora
3 Parts and location
4 Additional images
5 External links

[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. 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. The appendix can be removed with no damage or consequence to the patient.

[edit] Bacterial Flora

The large intestine houses over 700 species of bacteria that perform a variety of functions including 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:

Cecum - the first part of the large intestine
Vermiform appendix - small appendage on the cecum containing lymphatic tissue
Taeniae coli - three bands of smooth muscle
Haustra - bulges caused by contraction of taeniae coli
Epiploic appendages - small fat accumulations on the visceral peritoneum
Rectum
Anal canal - last segment of the large intestine
Internal anal sphincter - involuntary, smooth muscle
External anal sphincter - voluntary, skeletal muscle
Anus

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

Sigmoid colon and rectum, showing distribution of branches of inferior mesenteric artery and their anastomoses.

[edit] External links

Look up Large intestine in
Wiktionary, the free dictionary.

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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Anatomy of torso, digestive system: Gastrointestinal tract