colon

Examples of colon in the following topics:

• Polyps in the Colon

  • Colon polyps, abnormal growths of tissue in the colon, are of concern due to their potential for harboring cancerous cells.
  • Colon polyps are not commonly associated with symptoms.
  • Colon polyps are a concern because of the potential for colon cancer being present microscopically and the risk of benign colon polyps transforming over time into malignant ones.
  • Even though colon cancer is usually not found in polyps smaller than 2.5 cm, all polyps found are removed since the removal of polyps reduces the future likelihood of developing colon cancer.
  • Colonoscopies are preferred over sigmoidoscopies because they allow the examination of the entire colon, a very important aspect considering that more than half of the colonic polyps occur in the upper colon which is not reached during sigmoidoscopies.

• Diverticular Disease

  • Diverticulosis, also known as diverticular disease, is the condition of having outpocketings of the colonic mucosa and submucosa due to weaknesses of muscle layer in the colon wall.
  • The clinical forms of colonic diverticulosis are uncomplicated and complicated colonic diverticulosis.
  • The strength of the colon decreases with age in all parts of the colon, except the ascending colon.
  • Colonic diverticulosis increases in frequency with age.
  • Diverticulosis as seen endoscopically, showing characteristic diverticula in the colon, which are outpocketings of the colonic mucosa and submucosa through weaknesses in the muscle layers in the colon wall.

• Anatomy of the Large Intestine

  • The large intestine consists of the cecum and colon.
  • From here it continues up the abdomen (ascending colon), then across the width of the abdominal cavity (transverse colon), and then it turns down (descending colon), continuing to its endpoint at the anus (sigmoid colon to rectum to anus).
  • A schematic of the large intestine, with the colon marked as follows: cecum; 1) ascending colon; 2) transverse colon; 3) descending colon; 4) sigmoid colon, rectum, and anus.

• Digestive System Development

  • Components derived from the gut proper, including the stomach and colon, develop as swellings or dilatations of the primitive gut.
  • The midgut is the lower duodenum, leading to the first two-thirds of the transverse colon, jejunum, ileum, cecum, appendix, ascending colon, and first two-thirds of the transverse colon.
  • The hindgut includes the last third of the transverse colon, descending colon, rectum, and upper part of the anal canal.

• Abdominopelvic Regions

  • Pain in this region is associated with malrotation of the intestine and colon.
  • The right lumbar region consists of the gallbladder, the left kidney, part of the liver, and the ascending colon.
  • The left lumbar region consists of the descending colon, the left kidney, and part of the spleen.
  • It also contains the transverse colon (the section between the ascending and descending colons) and the bottom portions of both the left and right kidney.
  • The left illiac region contains part of the descending colon, the sigmoid colon, and the right illiac fossa.

• Colorectal Cancer

  • Colorectal cancer, commonly known as bowel cancer, is a cancer from uncontrolled malignant cell growth in the colon, rectum, or appendix.
  • Colorectal cancer, commonly known as bowel cancer, is a cancer from uncontrolled malignant cell growth in the colon, rectum, or appendix .
  • Greater than 75-95% of colon cancer occurs in people with little or no genetic risk.
  • People with inflammatory bowel disease, ulcerative colitis, and Crohn's disease, are at increased risk of colon cancer.
  • The interior surface of the colon shows an invasive colorectal carcinoma and two adenomatous polyps.

• Histology of the Large Intestine

  • The large intestine consists of the cecum, colon, rectum, and anal canal.
  • In histology, an intestinal crypt—called the crypt of Lieberkühn—is a gland found in the epithelial lining of the small intestine and colon.
  • A photograph of the large bowel (sigmoid colon) that shows multiple diverticula on either side of the longitudinal muscle bundle (Taenia coli).

• Anatomy of the Digestive System

  • Colon, which includes the ascending colon, transverse colon, descending colon, and sigmoid flexure.
  • The main function of the colon is to absorb water, but it also contains bacteria that produce beneficial vitamins like vitamin K.

• Defecation Reflex

  • If this urge is not acted upon, the material in the rectum is often returned to the colon by reverse peristalsis where more water is absorbed, thus temporarily reducing pressure and stretching within the rectum.
  • The additional fecal material is stored in the colon until the next mass 'peristaltic' movement of the transverse and descending colon.

• Digestive Processes of the Large Intestine

  • The colon absorbs vitamins created by the colonic bacteria—such as vitamin K (especially important as the daily ingestion of vitamin K is not normally enough to maintain adequate blood coagulation), vitamin B12, thiamine, and riboflavin.
  • Bacteria make up most of the flora in the colon and up to 60 percent of the dry mass of feces.
  • Image shows the relationship of the colon to the other parts of the digestive system.