Colon

Anatomy of the colon
The human digestive tract begins in the embryo as a single hollow gut tube, later specializing into distinct sections and budding off into the accessory organs of digestion. After digestion in the stomach, food passes into the intestines. The intestines are divided into two visually different sections - the small intestine which is followed by the colon (or large intestine). The colon has a wider circumference than the small intestine and the contents moves much slower. There is a higher proportion of bacteria in the colon, which aids in the digestion of substances such as cellulose and pectin.

During development, the digestive tract is connected to the celomic cavity by a mesenteric sheet which contains the blood and nerve supplies. In some parts of the digestive system, the mysentery fuses to the peritoneum that lines the celomic cavity and effectively secures that region of the digestive system in place - described as retroperitoneal because it is not actually within the peritoneal cavity. Sections where the mysentery persists as a connective sheet are described as intraperitoneal. The mysentery still contains the blood and nerve supplies of the corresponding section of the digestive tract, with a large surface area giving it a folded and creased appearance. Mysenteries allow greater movement and act as an anchor that tethers the digestive system to the peritoneal wall.

The abdominal section of the digestive tract consists of two layers of smooth muscle. The inner layer is circular and acts to constrict and apply pressure to the contents of the gut. Rhythmic contraction of the inner layer propels gut contents from one end of the intestine to the other in a movement called peristalsis. The outer layer of smooth muscle is longitudinal, controlling the length and tension of the digestive tract. In the colon it is confined to three bands known as the teniae coli.

Caecum
The caecum marks the divide between the small intestine and the colon, and is a short pouch of expanded colon. This is small in humans but is greatly enlarged in animals with high-cellulose diets, as it plays an important role in the fermentation and digestion of vegetation like grass and leaves. The caecum sits on the bottom right-hand side of the abdomen.

Ascending colon
The ascending colon begins from the caecum on the lower right-hand side of the abdomen and rises vertically upwards until it reaches the liver. Here the colon turns a corner, known as the right colic flexure, and becomes the transverse colon. The ascending colon is retroperitoneal, meaning that it's mysentery has fused with the peritoneum and it is immobilized.

Transverse colon
The transverse colon travels horizontally across the abdomen from the right colic flexure, passing beneath the stomach and above the coils of the small intestine. It lies behind the greater omentum, which is a connective tissue and mysenteric sheet attached to the bottom of the stomach. The transverse colon has a mysentery, allowing it to move. To the left of the stomach, the colon turns another corner (the left colic flexure) and becomes the descending colon.

Descending colon
The descending colon travels vertically down from the left colic flexure until it ends in the sigmoid colon. The descending colon is retroperitoneal and is immobilized like the ascending colon.

Sigmoid colon
The colon forms an s-shaped curve known as the sigmoid colon, which then leads to the rectum.

Microbiome of the colon
Gut Bacteria Could Be Key Indicator of Colon Cancer Risk http://www.sciencedaily.com/releases/2010/06/100622091738.htm

Computational model
Math Model of Colon Inflammation Singles out Dangerous Immune Cells http://www.sciencedaily.com/releases/2010/07/100722181313.htm

Colon Cancer
http://coloncancer.about.com/od/signsandsymptoms/a/Nausea_Vomiting.htm

Diseases of the colon
Ulcerative colitis http://en.wikipedia.org/wiki/Ulcerative_colitis

Following are the most common diseases or disorders of the colon:
 * Angiodysplasia of the colon
 * Appendicitis
 * Chronic functional abdominal painNF
 * Colitis
 * Colorectal cancer
 * Constipation
 * Crohn's disease
 * Diarrhea
 * DiverticulitisNF
 * Diverticulosis
 * Hirschsprung's disease (aganglionosis)
 * Ileus
 * Intussusception
 * Irritable bowel syndrome
 * Polyp (medicine) (see also Colorectal polyp)
 * Pseudomembranous colitis
 * Ulcerative colitis and toxic megacolon

http://en.wikipedia.org/wiki/Colon_(anatomy)

Source:

Cartmill, M., W.L. Hylander and J. Shafland 1987. Human Structure. Harvard University Press, Cambridge.