What is the Colon?

  If you recently heard someone talk about the colon, they were probably talking about an organ inside the human body, not to be confused with the punctuation mark - also known as the colon.  Over the years, there has been increasing awareness about Colonoscopy and Colon Cancer. Our purpose here is to explain what the human colon is, in an easy to digest way.

Colonoscopy Procedure

Understanding the context in which the word colon was used is also important. It is possible you heard about a common medical test used to screen for colon cancer, called a colonoscopy. During this test a thin, flexible, six-foot long tube with a camera is inserted through the anus. From there, the camera is used to examine the inside surface of the colon - which is where digested food is turned into feces and is also stored. This test is very important. There is high quality evidence which shows routine colonoscopy saves lives from colon cancer. Given this benefit, it is essential to understand what the colon is so you can make an informed decision to maintain good health.

Layers of the Digestive System

The human digestive system, for all intents and purposes, is one long pipe. Food and beverage enter the long pipe through the mouth. The contents then flow about 30 feet before exiting the other end of the pipe. This journey, from food to feces, takes 24 to 72 hours. A layer of muscle encompasses this pipe. Muscle contraction starts at the top of the pipe and progresses along the pipe’s length. One contraction at a time, it slowly pushes food through to the end. Several factors including the type and amount of food and beverage consumed, age, hormone levels, medication, and emotional status can shorten or lengthen this journey. If food and liquid travel too quickly to the end, the resulting feces will be loose and watery. Likewise, if food and liquid travel too slowly, the resulting feces is hard and dry. The major player in water absorption from digested food is the colon.

Anatomy of the Colon

The large intestine is the last 5 feet of the human digestive system. It is divided into four parts: cecum, colon, rectum and anal canal. If that wasn’t enough, the colon is then divided into four parts: ascending, transverse, descending, and the sigmoid colon.

The ascending colon is on the right side of the abdomen. To help visualize this, take your right hand and put it over the right side of your abdomen - this is where the ascending colon is. However, illustrations of the large intestine make the colon look like a perfectly straight pipe. This is rarely ever the case. There are twists and turns in the colon which are unique to each person. This is usually caused by differences in body fat content. Besides the fat located beneath the skin, there is also fat located inside the abdomen. This intra-abdominal fat is not usually seen outside the body. It is found packed between abdominal organs like the stomach, liver, intestines, etc. 

Another common cause of unique twists and turns in the colon is caused by abdominal adhesions. These are fibrous bands of tissue between abdominal organs. Usually these surfaces are slippery, which allows for movement of abdominal organs with body movement. However, when these bands restrict movement - organs get twisted and pulled out of place. The most common cause of abdominal adhesions is abdominal surgery. In fact, 93% of patients who have abdominal surgery go on to develop abdominal adhesions. [2] Unfortunately, these twists and turns in the colon can increase the chance of a tear in the colon during colonoscopy. That is why it is critical to chose an experienced endoscopist to perform the procedure. Here at Gupta Gastro, Dr. Rakesh Gupta has been performing colonoscopies for over 35 years.

Once digested food arrives in the ascending colon, the process of water and salt extraction starts. Rhythmic muscle contraction pushes digested food about 8 inches to the turn located beneath the liver, and then into the transverse colon. The transverse colon is 18 inches long, at the end of which the digested food is considered feces. Next, the feces turns a corner located beneath the spleen and is deposited in the descending colon. The descending colon’s main function is to store feces. However, some water extraction also happens here. 

The final segment of the colon is the sigmoid colon. It is named based on its shape which looks like the Greek letter sigma (ς). The sigmoid is the most muscular part of the colon, which gives it the power needed to push feces into the rectum. This causes the rectum to stretch and send a signal to the brain: it is time to visit the toilet.

Colon Polyps

There are some common disease processes which occur in the colon. First, and most worrisome, are colon polyps. A polyp is defined as an abnormal tissue growth. Colon polyps are important because they may be, or may turn into, colon cancer. Most polyps are harmless. However, because there is a possibility of malignant polyps - it is critical to remove all polyps and have them examined by an experienced pathologist. There are a few types of polyps which are commonly seen on pathology reports. The first is a hyperplastic polyp. This is simply an overgrowth of normal tissue and is not considered dangerous. Next, however, is an adenomatous polyp. While only a fraction of adenomas go on to become malignant - out of the colon polyps that are found to be malignant, nearly all of them are adenomatous. Polyps are a serious consideration about how soon repeat colonoscopy should be performed. A decision which is made on a case-by-case basis.

Diverticular Disease

The next, and most common disease in the colon, is diverticulosis. About half the population over the age of 60 is affected. Diverticulosis is a condition in which small pouches form in weak areas of the colon wall. These diverticula are caused by decades of excessive pressure in the colon - needed to propel dry, hard feces. A high-fiber diet promotes soft, bulky feces which can easily be propelled through the colon. This has been shown to decrease the incidence of diverticulosis. While these diverticula are asymptomatic for most people, under certain conditions they can become infected or bleed. Like the old saying goes: an ounce of prevention is worth a pound of cure. Well, in this case, 25 grams of fiber a day should do! [3]

In recent years there has been increased research, and headlines in the news, about the benefits of probiotics - especially for gastrointestinal disorders. Considering that the colon houses over 700 species of bacteria - this makes sense. [4] Bacteria in the colon ferment undigested polysaccharides, like starch, into gas. The bacteria are also involved in the production of vitamin K, biotin and antibodies produced by the immune system. Changes to the bacteria in the colon can significantly alter a person’s feeling of well-being. Events that can cause this include antibiotic use and gastroenteritis. However, it can be as simple as not consuming enough good bacteria. At Gupta Gastro, we carry the most up-to-date probiotics available and we can help you make the right choice to restore balance in your life.

With research, high-tech equipment and a knowledgeable team, Gupta Gastro will serve as your tool to fight against an assortment of health issues. We are here to help you feel better and to help you live longer. If you have any questions or concerns about your digestive health, please call our office to schedule an appointment or schedule an appointment online.