Colon
Anatomy
The colon is the final part of the digestive tract in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body and is the site in which flora-aided (largely bacterial) fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a major role in absorption of foods and nutrients. However, the colon does absorb water, potassium, and some fatty acids such as butyrate.
Structure
The colon consists of four sections: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. The term "colon" is sometimes used to refer to the entire large intestine.
Ascending Colon
The ascending colon is the first of four main sections of the colon. It is connected to the small intestine by a section of bowel called the cecum. The ascending colon runs upwards through the abdominal cavity toward the transverse colon for approximately eight inches (20 cm).
Transverse Colon
The transverse colon is the longest and most movable part of the colon. It crosses the abdomen from the ascending colon at the hepatic or right colic flexure with a downward convexity to the descending colon where it curves sharply on the left side below the ends of the eighth or ninth ribs and passes transversely from right to left toward the spleen.
Descending Colon
The descending colon is the part of the colon from the splenic flexure to the beginning of the sigmoid colon. One function of the descending colon in the digestive system is to store feces that will be emptied into the rectum.
Sigmoid Colon
The sigmoid colon is the part of the large intestine after the descending colon and before the rectum. The name "sigmoid" comes from the Greek letter sigma, which is 'S' shaped. The walls of the sigmoid colon are muscular, and contract to increase the pressure inside the colon, causing the stool to move into the rectum.
Function
The colon plays a very important role in how your body processes food. The colon removes water, salt, and some nutrients forming stool. Muscles line the colon's walls, squeezing its contents along. Billions of bacteria coat the colon and its contents, living in a healthy balance with the body.
Clinical significance
Various diseases and conditions can affect the function and structure of the colon, such as colorectal cancer, colitis, and diverticulitis. These conditions can cause a range of symptoms including inflammation, bleeding, and severe pain. Treatments for these conditions can include changes in diet, medication, and in some cases, surgery.