Jejunum

A vital section of the small intestine that plays a central role in nutrient absorption.

The jejunum is the middle section of the small intestine, located between the duodenum and the ileum. It is approximately 2.5 meters long and is characterized by its highly folded inner surface, which increases the area for absorption. The jejunum primarily absorbs carbohydrates, proteins, and fats, making it essential for digestion and nutrition.

Terminologia Anatomica

jejunum

System

Digestive system

Function

The primary function of the jejunum is to absorb nutrients from the digested food that passes through it. It does so through its specialized lining composed of villi and microvilli, which create a vast surface area ideal for nutrient uptake. The jejunum absorbs a significant portion of nutrients, including vital vitamins, minerals, and macronutrients, and plays a crucial role in maintaining the body's energy levels. Furthermore, the jejunum is involved in the process of transporting these absorbed nutrients into the bloodstream, where they can be delivered to cells throughout the body for use in various physiological functions, growth, and repair. Additionally, the jejunum produces digestive enzymes that aid in breaking down food particles, enhancing the absorption process.

Location

The jejunum is situated in the central part of the abdominal cavity, specifically in the left upper and lower quadrants. It follows the duodenum, which is approximately 25 centimeters long, and leads into the ileum, the final segment of the small intestine. The jejunum is anchored to the posterior abdominal wall by a structure called the mesentery, which contains blood vessels, lymphatics, and nerves that supply the jejunal tissue. Its position allows it to receive partially digested food from the stomach via the duodenum, where it continues the digestive and absorption processes.

Did You Know?

The jejunum is about 2.5 meters long, making it one of the longest segments of the small intestine.
The inner surface of the jejunum has a much thicker wall and a greater vascular supply than the ileum, enhancing its ability to absorb nutrients.
In a healthy adult, the jejunum absorbs approximately 90% of the water and nutrients from the food consumed.