The key difference between duodenum and jejunum is that the duodenum is C shaped and makes up the first portion of the small intestine, while the jejunum is a coiled tube and makes up the middle portion of the small intestine
The small intestine extends from the pylorus of the stomach to the junction between the cecum and ileum, which makes the longest part of the alimentary canal. It can be divided into three sections, including; duodenum, jejunum, and ileum. Although there are no clearly defined boundaries between these three parts, there are characteristic features that reflect their differences in function. The primary digestion and absorption mainly occur in the duodenum and jejunum.
CONTENTS
1. Overview and Key Difference
2. What is Duodenum
3. What is Jejunum
4. Duodenum vs Jejunum in Tabular Form
5. Summary – Duodenum vs Jejunum
What is Duodenum?
This is the first part of the small intestine that lies in between the pylorus and jejunum. It is ‘C’ shaped and about 10 inches long. The first part of this tube is very much similar to the stomach in structure. The first two inches of duodenum run upward and backward on the right side of the first lumbar vertebra, while the next 3 inches of it run vertically downward on the right side of the second and third lumbar vertebrae. The next 3 inches of duodenum runs horizontally to the left on the subcostal plane and follows the lower margin of the head of the pancreas. The rest of 2 inches of it runs upward and to the left to the duodenojejunal flexure. Duodenum basically receives the acidic chyme from the stomach, bile from the liver and gallbladder, and digestive enzymes from the bicarbonate from the pancreas. These digestive enzymes digest larger food particles into smaller fragments in this section.
What is Jejunum?
The jejunum is the second part of the small intestine. It is about 8 feet long and lies between the duodenum and ileum. Jejunum begins at the duodenojejunal flexure. The coils of the jejunum are freely mobile and are attached to the posterior abdominal wall by the mesentery of the small intestine. Jejunum has a wider bore, thicker walls, and more numerous microvilli on the mucus membrane. These microvilli increase the surface area of absorption and increase the efficiency of digestion. This part is specialized to absorb most monosaccharides and amino acids. The mesentery of the jejunum is made up of circular and longitudinal muscles, which help to move food along the elementary canal and thus give great mobility within the abdomen.
What is the Difference Between Duodenum and Jejunum?
Duodenum is C shaped and makes up the first portion of the small intestine, while jejunum is a coiled tube and makes up the middle portion of the small intestine. Thus, this is the key difference between duodenum and jejunum. Furthermore, the jejunum is longer than the duodenum. Moreover, the digestion of carbohydrates and protein take place in the duodenum, whereas the absorption of digested products takes place in the jejunum. Another difference between duodenum and jejunum is that submucosal Brunner’s glands are present in the duodenum, whereas they’re absent in the jejunum.
The below infographic presents the differences between duodenum and jejunum in tabular form for side-by-side comparison.
Summary – Duodenum vs Jejunum
The key difference between duodenum and jejunum is that the duodenum is C shaped and makes up the first portion of the small intestine, while the jejunum is a coiled tube and makes up the middle portion of the small intestine. Furthermore, the jejunum is longer than the duodenum.
Image Courtesy:
1. “2417 Small IntestineN” By OpenStax College – Anatomy & Physiology, Connexions Web site. , Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia