Jejunum

Definition

The jejunum is the middle section of the small intestine, situated between the duodenum and the ileum. It plays a vital role in the digestion and absorption of nutrients, characterized by its thicker walls and larger diameter compared to other sections of the intestine. Its extensive surface area, enhanced by numerous villi and microvilli, facilitates efficient nutrient absorption and is crucial for the body’s overall metabolic function.

5 Must Know Facts For Your Next Test

1. The jejunum accounts for about 2.5 meters of the total length of the small intestine, making it a significant site for nutrient absorption.
2. It has a rich blood supply, which helps transport absorbed nutrients to the rest of the body quickly.
3. The epithelial cells in the jejunum are specialized for absorbing carbohydrates, proteins, and lipids, highlighting its crucial digestive functions.
4. Unlike the duodenum, which primarily focuses on digestion, the jejunum is more involved in the absorption phase of nutrient processing.
5. Conditions such as celiac disease or Crohn's disease can severely impact the jejunum's ability to absorb nutrients, leading to malnutrition.

Review Questions

• How does the structure of the jejunum contribute to its function in nutrient absorption?
  • The jejunum is structurally adapted for efficient nutrient absorption due to its large surface area created by villi and microvilli. This extensive surface allows for more contact with digested food, facilitating higher absorption rates of essential nutrients like amino acids, sugars, and fatty acids. The thicker walls also indicate a greater capacity for transporting absorbed nutrients into the bloodstream.
• Discuss the differences in function between the jejunum and other parts of the small intestine, such as the duodenum and ileum.
  • The jejunum primarily focuses on nutrient absorption after initial digestion occurs in the duodenum. While the duodenum is involved in breaking down food using enzymes and bile, the jejunum excels at absorbing nutrients due to its specialized epithelial structure. In contrast, the ileum mainly absorbs vitamin B12 and bile salts before material enters the large intestine. This division of labor optimizes overall digestive efficiency.
• Evaluate how disorders affecting the jejunum can impact overall health and nutrition.
  • Disorders like celiac disease or Crohn's disease can significantly compromise the jejunum's ability to absorb nutrients effectively. When this part of the small intestine is damaged or inflamed, it leads to malabsorption syndromes where essential nutrients are not adequately absorbed into the body. This can result in deficiencies that affect overall health, manifesting as symptoms like fatigue, weight loss, and various metabolic disturbances, illustrating how critical this section is for maintaining nutritional balance.

Related terms

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

Intestinal Flora: The community of microorganisms residing in the intestines, which play a crucial role in digestion and overall gut health.

Peristalsis:

The wave-like muscle contractions that move food through the digestive tract, including the small intestine.