Understand the Role of the

Short Bowel Support
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A Patient’s Guide to Managing a Short Bowel

Get a complimentary book created by registered dietitian Carol Rees Parrish to help patients understand the workings of the gastrointestinal (GI) tract and how to maximize what’s left of theirs.



Short Bowel Syndrome and the digestive system

If you are a patient with Short Bowel Syndrome (SBS), you cannot absorb the proper amount of nutrients and fluids through your diet. This is because several components of the digestive system might not function properly in a person with SBS and/or may not exist due to surgical removal.

Digestive system

Digestive system

The digestive system is made of several components, and each contributes to the process in its own way. Learn more about a few of the components including:

About the digestive process

The stomach, the small intestine and large intestine work together to process food and water. The process begins in your mouth when food is broken down by chewing. The addition of saliva in your mouth begins the chemical processing that also takes place. Then, the food travels down the esophagus to your stomach.


After food is swallowed, it travels down the esophagus, a tube connecting your mouth to your stomach. The partially digested food is known as chyme. Once in your stomach, the food stimulates the release of substances (hormone regulators) that aid in digestion.

Small intestine

Once chyme leaves your stomach, it enters the small intestine, where it is broken down further. The normal length of the entire small intestine is approximately 12 to 21 feet, compared with less than 7 feet in many people with Short Bowel Syndrome.

The small intestine, also known as the small bowel, has 3 segments—the duodenum, the jejunum and the ileum. There are no lines separating these sections, but there are subtle differences between each section, and each performs an important role in absorbing nutrients.


The duodenum is a short funnel-shaped tube at the beginning of the small intestine. It receives chyme from the stomach, as well as enzymes from the pancreas and bile from the liver (delivered by the gallbladder) that help the body digest food. The duodenum absorbs proteins and carbohydrates.


The jejunum is the middle section of the small intestine. It connects the duodenum and the ileum. The jejunum absorbs proteins, carbohydrates, vitamins and minerals.


The ileum is the last section of the small intestine and connects to the large intestine. The ileum mainly absorbs water, bile salts and vitamin B12 from chyme that were not absorbed by the jejunum.

Because the intestines are not as long in people with SBS, there is less surface space for intestinal villi. The reason villi are important is because they help maximize the surface for absorption. Each one contains 500 smaller structures known as microvilli. There are approximately 10 billion microvilli in one square inch of your small intestine. Nutrients are absorbed through the villi walls and enter your bloodstream.

Ileocecal valve

The ileocecal valve is so named because it connects the small intestine to the large intestine. The ileocecal valve plays a vital role in preventing bacteria in the large intestine from getting into the small intestine. It also holds chyme in the smallbowel, allowing more time for the absorption of nutrients.

Large intestine

Similar to the small intestine, the large intestine can be divided into smaller parts, or segments. The large intestine, sometimes called the colon, is the last part of the digestive system. It connects the small intestine to the rectum. After the small intestine has absorbed nutrients from food, the main job of the large intestine is to remove water from chyme and prepare the final waste material for elimination through the rectum.


The cecum is the first part of the large intestine. After traveling through the small intestine and entering the large intestine through the ileocecal valve, chyme then enters the cecum, which is shaped like a pouch.

Ascending colon

The muscles of the ascending colon push the chyme upward, absorbing water in the process. This takes approximately 8 hours for a person with normal anatomy.

Transverse colon

The transverse colon is the middle segment of the colon and crosses the abdomen. Water continues to be absorbed as chyme travels across this segment for approximately 6 to 8 hours for a person with normal anatomy.

Descending colon

The descending colon is the final segment of the large intestine. Chyme takes approximately 4 hours to move down this segment, where it becomes more solid and ready for elimination through the rectum.

Intestinal Absorption

Intestinal villi. The inside wall of the intestine is called the lumen and the microscopic lining of the lumen is called the mucosa. As chyme moves along the mucosa, tiny pieces of nutrients attach to small fingerlike structures called intestinal villi. The reason villi are important is because they create a larger surface area in the lumen to maximize absorption. Each one contains approximately 500 smaller structures known as microvilli. There are approximately 10 billion microvilli in one square inch of the small intestine. Nutrients are absorbed through the villi walls and enter the bloodstream.


Hormones are substances produced in the body that control cells or organs. They are essential for every activity of daily living, including the processes of digestion.

Words appearing on this site in purple are defined in the Glossary. If you are unfamiliar with any of these words, just click on them for a definition.