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The Colon: What it is, What it Does

The Colon: What it is, What it Does | ASCRS

Alternate Titles: 
Colon: What it is, What it Does



The colon is also known as the large bowel or large intestine. It is an organ that is part of the digestive system (also called the digestive tract) in the human body. The digestive system is the group of organs that allow us to eat and to use the food we eat to fuel our bodies.


The colon plays a very important role in how our bodies use the food we eat. Here is how food travels through the body.

  1. Food begins in the mouth where it is chewed by the teeth into smaller pieces. The salivary glands release juices to help, and the tongue and saliva turn the food into even smaller pieces that will fit into the esophagus. The esophagus is a 10-inch-long tube that connects to the stomach. Muscles in the esophagus move food into the stomach.
  2. In the stomach, gastric juices — protein substances called enzymes — break down the food into smaller bits. The stomach has powerful muscles that churn up the food until it’s a creamy liquid. This material moves into the small bowel.
  3. In the small bowel, the food particles get even smaller. More juices from the pancreas, liver and gallbladder mix together in the small bowel. Here is where all the important vitamins and nutrients in food move through the blood vessels that are in the lining of the small bowel. The blood takes the nutrients to other organs in the body. The nutrients are used to help repair cells and tissue.
  4. What is left over, which is mostly liquid, then moves into the colon. The water is absorbed in the colon. Bacteria in the colon break down the remaining material. Then the colon moves the leftover material into the rectum.
  5. The rectum is like a storage-holder for this waste. Muscles in the rectum move the waste, called stool, out of the body through the anus.

Healthy eating is good for your overall health, but having a low-calorie, high-fiber diet that includes many fruits and vegetables is important to a healthy colon. A healthy colon will rid your body of the leftovers it no longer needs. Your stool is filled with bacteria, so it is important to pass this out of your body. If your colon isn’t working the way it should, you will experience problems such as bloating, gas and pain.

Talk with your health care provider about colorectal cancer. Colorectal cancer is preventable, and is easy to treat and often curable when detected early. Ask your health care provider what kind of screening test you should have and when. 


Colon and rectal surgeons are experts in the surgical and non-surgical treatment of diseases of the colon, rectum and anus. They have completed advanced surgical training in the treatment of these diseases as well as full general surgical training. They are well-versed in the treatment of both benign and malignant diseases of the colon, rectum and anus and are able to perform routine screening examinations and surgically treat conditions, if indicated to do so.


The American Society of Colon and Rectal Surgeons is dedicated to ensuring high-quality patient care by advancing the science, prevention and management of disorders and diseases of the colon, rectum and anus. These brochures are inclusive but not prescriptive. Their purpose is to provide information on diseases and processes, rather than dictate a specific form of treatment. They are intended for the use of all practitioners, health care workers and patients who desire information about the management of the conditions addressed. It should be recognized that these brochures should not be deemed inclusive of all proper methods of care or exclusive of methods of care reasonably directed to obtain the same results. The ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of all the circumstances presented by the individual patient.