Jejunum

Definition

The jejunum is the middle section of the small intestine, located between the duodenum and the ileum. It plays a crucial role in the digestion and absorption of nutrients from food, making it essential for overall digestive health. The jejunum has a large surface area due to its numerous folds and villi, which enhance nutrient absorption, and is also rich in blood supply, allowing for efficient nutrient transport into the bloodstream.

5 Must Know Facts For Your Next Test

1. The jejunum constitutes about 2.5 meters of the small intestine's length and is primarily responsible for absorbing carbohydrates and proteins.
2. Its inner surface is highly specialized with folds, called plicae circulares, and finger-like projections known as villi that increase its absorptive capacity.
3. The jejunum has a thicker wall compared to the ileum and a more vascularized structure, which helps in transporting absorbed nutrients more efficiently.
4. Enzymes secreted by the pancreas and bile from the liver continue to act on food in the jejunum, breaking down nutrients for absorption.
5. Disorders affecting the jejunum can lead to malabsorption syndromes, resulting in nutrient deficiencies and related health issues.

Review Questions

• How does the structure of the jejunum facilitate its role in nutrient absorption?
  • The structure of the jejunum is highly specialized to maximize nutrient absorption. It features numerous folds called plicae circulares and many villi, which increase its surface area significantly. This large surface area allows more contact with digested food, enhancing the efficiency of nutrient absorption into the bloodstream. Additionally, its rich blood supply ensures that absorbed nutrients are quickly transported to other parts of the body.
• What is the relationship between the jejunum and other sections of the small intestine in terms of digestive function?
  • The jejunum works closely with both the duodenum and ileum to ensure efficient digestion and nutrient absorption. The duodenum is where initial digestion occurs, receiving digestive enzymes from the pancreas and bile from the liver. Once food passes into the jejunum, it undergoes further digestion, with a focus on absorbing carbohydrates and proteins. Finally, any remaining undigested nutrients move into the ileum for additional absorption before reaching the large intestine.
• Evaluate how disorders of the jejunum can impact overall health and nutrition.
  • Disorders affecting the jejunum can lead to significant health issues due to its critical role in nutrient absorption. Conditions such as celiac disease or Crohn's disease can damage the lining of the jejunum, impairing its ability to absorb carbohydrates, proteins, and essential vitamins. This malabsorption can result in nutrient deficiencies, leading to symptoms like weight loss, fatigue, anemia, and weakened immune function. Addressing these disorders is vital for restoring proper nutrient intake and maintaining overall health.

Related terms

Duodenum: The first part of the small intestine where initial digestion occurs, receiving bile and pancreatic enzymes.

Ileum: The final section of the small intestine, responsible for absorbing nutrients not absorbed by the jejunum and connecting to the large intestine.

Villi:

Small finger-like projections lining the walls of the small intestine that increase surface area for nutrient absorption.