Ileum

Definition

The ileum is the final section of the small intestine, connecting the jejunum to the large intestine. It plays a crucial role in the absorption of nutrients, particularly vitamin B12 and bile salts, and is characterized by its specialized structure that allows for efficient nutrient uptake. The ileum also contains lymphoid tissue, which contributes to immune function within the gastrointestinal tract.

5 Must Know Facts For Your Next Test

1. The ileum measures about 3-4 meters in length and is highly folded to maximize surface area for absorption.
2. It is where most vitamin B12 and bile salts are absorbed into the bloodstream, essential for metabolic processes.
3. The ileocecal valve separates the ileum from the large intestine, regulating the flow of material and preventing backflow.
4. The presence of Peyer’s patches in the ileum helps in immune surveillance by monitoring gut flora and responding to pathogens.
5. Disorders affecting the ileum, such as Crohn's disease, can lead to malabsorption and nutritional deficiencies due to impaired function.

Review Questions

• How does the structure of the ileum facilitate its function in nutrient absorption?
  • The structure of the ileum includes numerous villi and microvilli that significantly increase its surface area, allowing for enhanced nutrient absorption. Additionally, the presence of specialized transport proteins facilitates the uptake of specific nutrients like vitamin B12 and bile salts. The folds in the ileal lining also create more surface area for interaction with digestive contents, making absorption more efficient.
• What is the role of Peyer’s patches in the ileum, and how do they contribute to gastrointestinal health?
  • Peyer’s patches are clusters of lymphoid tissue located in the ileum that play a vital role in monitoring intestinal bacteria. They contribute to gastrointestinal health by facilitating immune responses against pathogens while maintaining tolerance to non-harmful microbes. This balance helps prevent infections and maintains overall gut health, demonstrating how immune function is integrated with digestive processes.
• Evaluate how diseases affecting the ileum can impact overall nutrient absorption and health outcomes.
  • Diseases such as Crohn's disease or celiac disease can severely impact the ileum’s ability to absorb nutrients effectively. This leads to malabsorption issues that result in deficiencies of critical nutrients like vitamin B12, iron, and folate, affecting energy levels and overall health. Chronic inflammation or damage to the ileal lining can also disrupt gut flora balance, leading to further complications such as increased susceptibility to infections and autoimmune responses.

Related terms

Jejunum: The jejunum is the middle section of the small intestine, situated between the duodenum and the ileum, primarily responsible for nutrient absorption.

Villi: Villi are small, finger-like projections lining the inner surface of the small intestine that increase the surface area for absorption of nutrients.

Peyer’s Patches: Peyer’s patches are specialized lymphoid follicles found in the ileum that play a key role in the immune response by monitoring intestinal bacteria and preventing the growth of pathogenic bacteria.