What Is the Duodenal Bulb?

A human stomach with the c-shaped duodenum shown below.
The gastrointestinal tract is the soft tissue tube that begins at the mouth and ends with the anus and includes all the digestive organs in between.
Villi, or tiny projections, line the walls of the intestines.
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  • Written By: B. Chisholm
  • Edited By: Nancy Fann-Im
  • Last Modified Date: 25 August 2014
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The duodenal bulb is part of the human gastrointestinal tract. It is the section of the duodenum closest to the stomach and is usually about 5 centimeters long. The duodenum is the small intestine's first section. It connects the stomach to the jejunem and is mainly responsible for the breakdown of food by enzymes.

Digestion is a complex and intricate process and begins the moment food is placed in the mouth and chewed. The digestive system, or gastrointestinal tract, stretches from the mouth through the esophagus, stomach and intestines, and all the way to the anus. Digestion occurs throughout the food's journey. Different body parts are responsible for different processes, from food breakdown to extraction of necessary nutrients and energy sources, to disposal of unneeded or toxic by-products.

The duodenal bulb starts at the pylorus and ends at the neck of the gall bladder. It is behind the gall bladder and liver but in front of the pancreas. It is referred to as the duodenal bulb because it is slightly rounded and has a smoother surface than the rest of the duodenum, which has more folds and villi. Villi are hair-like extensions of the mucosa that line the intestines and increase the exposed area for absorption.

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The duodenal bulb is the first section of the duodenum, which is responsible for the breakdown of food and regulating the emptying of the stomach. Hormones are released in response to acidic and fatty stimuli, causing the pyloric sphincter, a ring of smooth muscle at the end of the stomach, to relax, thus allowing the food to pass through into the duodenal bulb. The liver, gall bladder and pancreas are all involved in the digestion of food in the duodenum.

Duodenal ulcers may occur in the duodenal bulb. A number of mechanisms are placed throughout the digestive system to protect the mucosa from acid. When an alteration occurs in these protective factors, either due to intrinsic factors or extrinsic factors such as non-steroidal anti-inflammatory use, ulcers may result. They can occur anteriorly, meaning in the front, or, in rare instances, posteriorly, or behind. Depending on their position, duodenal ulcers may result in perforation or bleeding and may require medical treatment.

Once food has passed through the duodenum it continues on through the jejunem, ileum and then the large intestine, which is commonly referred to as the colon. Salt and water absorption as well as fermentation of unabsorbed material occurs in the colon. The colon joins the rectum, in which feces are stored until expulsion via the anus.

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indigomoth
Post 3

@pastanaga - Well, to some extent it's the acid that causes the ulcer. Even though it's the result of a bacterial infection, it's the acid that actually ends up wearing away the infected cells and exposing the stomach lining.

It isn't pleasant, but unfortunately most of the early symptoms aren't all that different from any other stomach complaint. Just nausea, pain, bloating and so forth.

pastanaga
Post 2

@croydon - Well, the gall bladder does produce bile, which is some of the stuff that gets vomited up when people do that, and it passes through the duodenal bulb as well I think.

That's why a duodenal bulb ulcer is so painful. I always thought that it was only stomach ulcers that would be particularly painful, since that's where the acid is, and ulcers in other parts of the digestive system wouldn't be as bad.

But there's acid and bile in the duodenal bulb as well, and it's supposed to be incredibly painful if you get an ulcer there.

croydon
Post 1

I was reading on a forum recently about a girl's problems with her stomach after she went into recovery from an eating disorder. She didn't go into specifics about the eating disorder, but it sounds like it was probably anorexia and bulimia.

And she was still having pain from her gall bladder and general stomach area a couple of years after she began to try and eat more normally.

At first I didn't know why her gall bladder should be affected at all, but now that I can see the duodenal bulb anatomy more clearly it doesn't surprise me. Since the gall bladder is attached, it probably was affected physically by what was going on.

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