Jejunum

Definition

The jejunum is the second part of the small intestine, situated between the duodenum and the ileum. It plays a crucial role in the digestive process by absorbing nutrients from digested food. Its highly folded inner surface is lined with villi and microvilli, which increase the surface area for absorption and are essential for nutrient uptake.

5 Must Know Facts For Your Next Test

1. The jejunum makes up about 2.5 meters (8 feet) of the small intestine's length, playing a significant role in nutrient absorption.
2. It has a thicker wall and a more extensive blood supply compared to the ileum, highlighting its function in nutrient uptake.
3. The inner lining of the jejunum contains numerous folds called plicae circulares, enhancing its ability to absorb nutrients efficiently.
4. The jejunum absorbs most carbohydrates, proteins, and fats during digestion, making it vital for nutrition.
5. Disorders affecting the jejunum can lead to malabsorption syndromes, resulting in nutrient deficiencies and other health issues.

Review Questions

• How does the structure of the jejunum facilitate its role in nutrient absorption?
  • The structure of the jejunum is specifically designed to maximize nutrient absorption. Its highly folded inner surface contains villi and microvilli, which significantly increase the surface area available for absorption. The rich blood supply ensures that absorbed nutrients are quickly transported throughout the body. This unique architecture allows for efficient uptake of essential nutrients from digested food.
• Compare and contrast the functions of the jejunum with those of the duodenum and ileum in the digestive process.
  • While all three parts of the small intestine play roles in digestion, they have distinct functions. The duodenum primarily focuses on chemical digestion, mixing chyme with bile and pancreatic juices. In contrast, the jejunum specializes in absorbing nutrients such as carbohydrates and proteins. Finally, the ileum mainly absorbs vitamin B12 and bile salts. Together, these sections work collaboratively to ensure effective digestion and nutrient absorption.
• Evaluate how disorders affecting the jejunum could impact overall health and nutrition.
  • Disorders affecting the jejunum can severely disrupt nutrient absorption, leading to various health issues such as malnutrition and deficiencies. Conditions like celiac disease or Crohn's disease can damage its lining, impairing its ability to absorb carbohydrates, proteins, and fats effectively. This malabsorption can result in symptoms like fatigue, weight loss, and gastrointestinal distress. Understanding these connections emphasizes how critical a healthy jejunum is to overall well-being.

Related terms

Duodenum: The first section of the small intestine where most chemical digestion occurs, receiving chyme from the stomach along with bile and pancreatic juices.

Ileum: The final part of the small intestine, responsible for absorbing vitamin B12 and bile salts, before the contents pass into the large intestine.

Villi: Small, finger-like projections that line the inner surface of the small intestine, increasing the surface area for absorption of nutrients.