The colon is the last part of the gastrointestinal tract situated in the abdomen like an “M”. This term often refers to the large intestine. The colon extends from the cecum up the right side of the abdomen, across to the left side, then down the left side, and finally loops to connect with the rectum. The structure of the colon is classified into four parts: ascending colon, transverse colon, descending colon, and sigmoid colon. Like the rest of the gastrointestinal tract, the colon consists of the mucosa, submucosa, muscularis, and serosa four types of tissue. The purpose of the colon is to absorb the remaining fluids and salts of the chyme from the small intestine, lubricate waste products and store these products before they are ready to enter the rectum. In addition, several vitamins such as vitamin K, B, and biotin are produced and released by the bacterium residing in the colon. Disorders associated with the colon range from diarrhea, constipation, colitis to the more serious megacolon and cancer. A variety of target molecules expressed on the colon tissue are widely applied in research.
