Large Intestine Parts and Functions

The large intestine represents the end of the digestive tract. It connects with the small intestine at the cecum, ascends up and across the abdomen and then descends down to the rectum. What are the functions for its components? What kind of health problems can we have in large intestine?


Function of Large Intestine

The large intestine is primarily responsible for removing water from the contents of the intestine and making it ready for removal from the body. Its functions are:

1. Absorb Water

Within 24 hours after eating, undigested food moves from the small intestine into the large. At this point, most of the digestive process is complete. One of the primary functions of the large intestine is to absorb water and prepare the waste as a solid stool that will be expelled from the body.

2. Absorb Vitamins

There are a number of beneficial bacteria that normally live in the large intestine and play an important role in breaking down undigested sugars and fibers into fatty acids. These commensal bacteria also create the gas that is composed of methane, hydrogen sulfide, carbon dioxide and other gases. This flatus is the foul-smelling result of the breakdown of the sugars by the bacteria. The beneficial bacteria produce many vitamins, of which are Vitamin K and Biotin that are absorbed back into the body.

3. Reduce Acidity and Protect from Infections

The fatty acids that are produced by the bacteria in the large intestine cause an acidic environment in the gut. The large intestine produces alkaline solutions that help to reduce the acidity and balance the pH in the large intestine. The mucous lining of the large intestine acts as a protective layer that prevents harmful bacteria from being reabsorbed into the body.

4. Produce Antibodies

A little-known function of the large intestine is that it produces antibodies that help to boost immunity. It is believed that the appendix may have been a major producer of antibodies at some point in the evolutionary process.

Components of Large Intestine and Their Functions

What is the function of large intestine? The large intestine is composed of several very distinctive parts:


Role and Function


The caecum is the part of the large intestine that provides the connection between the small intestine and the colon of the large intestine. This small pouch is connected to the small intestine by a valve that controls the amount of material that moves into the colon. As material enters the cecum, the pouch expands and begins to move the undigested food, vitamins and water into the colon.


Attached to the cecum, the appendix is a small projection that may have been a major antibody producer. In modern man, the appendix does not seem to have any function. When it becomes infected, it is known as appendicitis which is cured by the use of surgery.


The colon is the largest part of the large intestine that connects with the cecum in the lower right abdomen. The ascending colon moves up through the abdomen and becomes the transverse colon when it moves across the abdomen from the right side to the left. When the colon turns down on the left side of the abdomen, it becomes the descending colon. Finally, the sigmoid colon is the connection between the descending colon and the rectum or anus.

The colon is where most of the functions of the large intestine happen – water and vitamins are absorbed and alkaline solutions and antibodies are produced. The stool that will be excreted is formed here. At the end of the large intestines, the sigmoid colon contracts forcefully causing the stool to be moved into the rectum.


Finally, the rectum stores the stool until it is expelled from the body.

Problems of Large Intestine

When answering what is the function of large intestine, we should also know that there are several common problems and a few serious conditions that can occur in the large intestine:




Constipation is a common problem of the large intestine in which the stool becomes hard to expel. This problem is usually caused by slow movement of waste material through the digestive tract. This, in turn, causes too much water to be absorbed resulting in a dry, hard stool. This condition can also be caused by neurological problems that prevent the rectum from signaling the need for defecation. In addition, stress can cause a suppression of defecation. If the individual’s diet does not contain enough fiber, movement of material can be slowed. For most people who suffer from constipation, eating more fiber and drinking more water may help resolve the problem.


On the other hand, when material moves through the large intestine too quickly, less water is absorbed and diarrhea can result. The causes of diarrhea can include a diet too high in fiber, infection, stress or a myriad of other issues that cause the body to want to expel material more quickly from the body.

Intestinal Gas

The gas produced by the interaction between the commensal bacteria and undigested food can be embarrassing and very painful. Methane, carbon dioxide, and hydrogen sulfide combine to produce the foul smell associated with intestinal gas. Certain foods can produce gas in some people. Avoiding beans, bran, cabbage, onions, milk, and broccoli can help prevent gas in people who are sensitive to these foods.

Serious Conditions

Most of the conditions outlined above are an inconvenience but there are several serious conditions that must be medically or surgically treated.

  • Diverticulosis is a weakening of the wall of the large intestine leading to pouching of the inner membrane. These pouches can become infected requiring antibiotics or surgery. Increasing dietary fiber may help prevent this condition.
  • Ulcerative colitis is an inflammation of the lining of the colon. This condition can result in pain, weight loss and diarrhea. Drugs or surgery are often required to treat this disorder.
  • Colorectal cancer is the second most common cancer in the United States. Common symptoms include: a change in bowel movements, bloody stools, and sometimes abdominal pain. Routine colonoscopy can catch colorectal cancer at early stages when surgery can cure the disorder.
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