What Is the Colon’s Function?

Doctor showing a diagram of the colon, or large intestine

Last Updated: October 3, 2023

The colon is a crucial component of the digestive process. Its main function is to remove waste from your body as food moves through the digestive system — the complex system composed of organs that convert food into fuel for our bodies.

The colon is the longest part of the large intestine, also known as the bowel. It is interconnected with other parts of the body that serve different functions to break down food.

Here we’ll go into more detail about the digestive system and the colon’s function.

How Does the Digestive Process Work?

As you eat, chew, and swallow, food travels through the esophagus and connects to the stomach. Food in the stomach dissolves into a liquid and moves to the small intestine. The small intestine, or small bowel, continues to break down food in conjunction with the liver, pancreas, and gallbladder.

Once the food’s nutrients are absorbed, the remaining liquid is processed to the colon. The colon absorbs the water while bacteria break down the residual material. After this, the colon directs trace materials to the rectum.

The rectum contains the waste from the digestive process. Muscles in the rectum move the stool (fecal waste) to exit the body through the anus.

The colon is essential to maintain the body’s fluid and electrolyte levels. A healthy colon can help regulate the body’s digestive system and prevent serious illness.

A healthy diet consisting of low-calorie, high-fiber meals is necessary for good colon health. In addition to diet and nutrition, routine screening and physical examinations are recommended to avoid diseases of the colon, rectum, and anus.

Anatomy of the Colon

Chart depicting the anatomy of the large intestine

It’s important to understand the anatomy of the colon to maintain healthy digestive habits. The colon (large intestine) has six parts:

  • Cecum
  • Ascending colon
  • Descending colon
  • Sigmoid colon
  • Transverse colon
  • Rectum

Each area of the colon is correlated to its:

  • Shape
  • Length
  • Placement
  • Function to discard waste materials

The colon begins where the small intestine ends, at the cecum, and ends at the rectum. The cecum is the widest portion of the colon, located on the bottom right side of the stomach. An estimated 15% of colon-related cancer metastasizes at the cecum.

The liver and stomach are in close proximity to the transverse and ascending colon. An ascending colon varies in length and is found within range of the cecum in the abdomen.

The ascending and descending colon are connected by a transverse colon that stretches across the length of the stomach — you can locate your descending colon left-centered in the abdomen, near the spleen.

The descending colon allows the sigmoid and transverse colon to meet. The sigmoid colon is the remaining portion of the colon that connects to the rectum and usually has an ‘S’-shaped curve.

The digestive process concludes when the rectum collects stool and allows waste to exit the body as a bowel movement.

Portions of the Colon

The colon is made up of four portions. Each anatomical portion of the colon has a different function:

  • Mucosa: The mucosa surface is called the epithelium. The mucosa is the first layer of the colon and provides lubricant to assist in the passage of stool through the colon. The mucosa is divided into three sub-tissues:
  • Submucosa: The layer of the colon filled with sensitive nerve endings, blood vessels, and connective tissue that supports the mucosa.
  • Muscularis propria: The second to last portion of the colon is comprised of an opposite-facing dual layer of muscle tissue. Because the layers extend horizontally and encompass the colon, cancers in this area tend to spread to other body parts.
  • Serosa: This is the outer area of the colon. If cancer develops within your serosa, it has metastasized and will spread outside of the colon.

How To Maintain Good Colon Health

A healthy colon absorbs nutrients well and aids in proper digestion. Consuming nutrients through a whole-food diet is crucial to the health of your colon.

Consuming refined sugar and flour, eating too much red meat, and excessive alcohol use can harm your colon health. Avoiding these types of food can help you to lose weight as well.

A high-fiber, balanced diet combined with healthy habits — like regular exercise — can decrease your risk for colon-related cancers. Staying hydrated, avoiding smoking, and limiting alcohol intake are proactive ways to keep your colon healthy.

Incorporating whole grains, vegetables, and fruits into your daily meals can decrease your risk for colon cancer as well.

It’s important to understand that colon health plays a huge part in your overall long-term health. A healthy colon and good dietary choices will improve your digestion and make you feel great.

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