Anatomy and Physiology of the Colon

To better understand the health of the digestive system and colon, it is helpful to first understand the different parts of the colon and their specific functions. This can help you become a stronger advocate for your own health and may grant you further insight into how your body works.

The colon is made up of 6 parts all working collectively for a single purpose. Their purpose is ridding the body of toxins that have entered the body from food sources, environmental poisons, or toxins produced within the body. The colon’s role is to transfer nutrients into the bloodstream through the absorbent walls of the large intestine while pushing waste out of the body. In this process, digestive enzymes are released, water is absorbed by the stool, and a host of muscle groups and beneficial microorganisms work to maintain the digestive system.

Overview of the Colon’s Anatomy

The colon is approximately 4.5 feet long, 2.5 inches wide, and is a muscular tube composed of lymphatic tissue, blood vessels, connective tissue, and specialized muscles for carrying out the tasks of water absorption and waste removal. The tough outer covering of the colon protects the inner layer of the colon with circular muscles for propelling waste out of the body in an action called peristalsis. Under the outer muscular layer is a sub-mucous coat containing the lymphatic tissue, blood vessels, and connective tissue. The innermost lining is highly moist and sensitive, and contains the villi- or tiny structures providing blood to the colon.

The colon is actually just another name for the large intestine. The shorter of the two intestinal groups, the large intestine, consists of parts with various responsibilities. The names of these parts are: the transverse colon, ascending colon, appendix, descending colon, sigmoid colon, and the rectum and anus.

Parts of the Colon:

Transverse, Ascending, and Descending Colons

The transverse, ascending, and descending colons are named for their physical locations within the digestive tract, and corresponding to the direction food takes as it encounters those sections. Within these parts of the colon, contractions from smooth muscle groups work food material back and forth to move waste through the colon and eventually, out of the body. The intestinal walls secrete alkaline mucus for lubricating the colon walls to ensure continued movement of the waste.

The ascending colon travels up along the right side of the body. Due to waste being forced upwards, the muscular contractions working against gravity are essential to keep the system running smoothly. The next section of the colon is termed the transverse colon due to it running across the body horizontally. Then, the descending colon turns downward and becomes the sigmoid colon, followed by the rectum and anus.

Ileocecal and Cecum Valves

The ileocecal valve is located where the small and large intestines meet. This valve is an opening between the small intestine and large intestine allowing contents to be transferred to the colon. The cecum follows this valve and is an opening to the large intestine.

The Rectum and the Anus

The rectum is essentially a storage place for waste and is the final stop before elimination occurs. The “tone” of the muscles of the anal sphincter and a person’s ability to control this skeletal-muscular system are vital for regulating bowel movement urges. When elastic receptors within the rectum are stimulated, these nerves signal that defecation needs to occur. In other words, these muscle and nerve groups convey when a bowel movement is necessary but allow a person to control when waste will actually be removed, as the final step in the digestive process. The anus is the last portion of the colon, and is a specialized opening bound with elastic membranes, sensitive tissues, and muscles and nerves allowing it to stretch for removing bowel movements of varying sizes. If, for example, you suffer from constipation, these tissues can become damaged and lose their ability to function normally if waste has to be forced out or remains in the body for prolonged periods. So it’s definitely good practice to keep things moving along at a regular pace. Ideally, you should have two bowel movements per day but at least once a day is pretty good; anything less than that could spell trouble for not only your digestive health but general health as well.

Physiology of the Colon

To summarize, approximately 500 ml (milliliters) of food pass through the colon daily. The various sections of the digestive tract absorb and remove water, propel waste throughout the long system of muscular tubes, work to keep the body alkalized, and accommodate the colonization of billions of beneficial microorganisms to aid us in breaking down waste matter. Regardless of the depth of your knowledge regarding the colon’s functions, please realize the importance of its functions for promoting overall health. Be good to your body on the inside as well as out by following a healthful diet, drinking ample of water, and keeping all your biological systems well maintained with stimulating exercise and by getting plenty of rest.

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