Ileum

Definition

The ileum is the final section of the small intestine, following the jejunum and preceding the cecum of the large intestine. It plays a crucial role in the absorption of nutrients, including vitamins, bile salts, and any remaining nutrients that were not absorbed in earlier parts of the digestive tract. The ileum is characterized by its thinner walls compared to other sections, along with numerous villi and microvilli that enhance its absorptive surface area.

5 Must Know Facts For Your Next Test

1. The ileum is typically about 3-4 meters long in adults and contains a high density of lymphoid tissue known as Peyer's patches, which play a role in immune function.
2. One of the key functions of the ileum is the absorption of vitamin B12 and bile salts, which are critical for digestion and metabolic processes.
3. The ileocecal valve regulates the flow of material from the ileum into the cecum, preventing backflow into the small intestine.
4. Unlike the duodenum and jejunum, which have thicker walls and more circular folds, the ileum has fewer folds and is thinner in structure.
5. Disorders affecting the ileum can lead to malabsorption syndromes, where nutrients are not adequately absorbed, leading to deficiencies.

Review Questions

• How does the structure of the ileum contribute to its function in nutrient absorption?
  • The structure of the ileum is specifically adapted to maximize nutrient absorption. It features numerous villi and microvilli that significantly increase its surface area, allowing for more efficient absorption of vitamins and nutrients. Additionally, its thinner walls facilitate easier passage of absorbed substances into the bloodstream, making it a vital area for nutrient uptake.
• What roles do Peyer's patches in the ileum play in overall digestive health?
  • Peyer's patches are specialized lymphoid tissues located within the ileum that serve a critical role in immune surveillance. They monitor intestinal bacteria and prevent harmful pathogens from entering the bloodstream. This immune function is essential for maintaining gut health and preventing infections while also supporting nutrient absorption by ensuring a balanced gut microbiome.
• Evaluate how disorders affecting the ileum can lead to broader health issues beyond just digestive problems.
  • Disorders affecting the ileum, such as Crohn's disease or celiac disease, can lead to significant malabsorption of essential nutrients like vitamin B12 and bile salts. This malabsorption not only results in digestive issues but can also cause systemic problems such as anemia, osteoporosis, and neurological disorders due to vitamin deficiencies. Thus, impairments in ileal function can have widespread health implications that extend beyond just gastrointestinal symptoms.

Related terms

Villi: Small, finger-like projections on the surface of the small intestine that increase the surface area for absorption.

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

Cecum: The first part of the large intestine, where undigested food material from the ileum enters.