Villi

Definition

Villi are small, finger-like projections that extend into the lumen of the small intestine. They increase the surface area for nutrient absorption and contain blood vessels and lacteals for nutrient transport.

5 Must Know Facts For Your Next Test

1. Villi are covered with even smaller hair-like structures called microvilli, forming a brush border.
2. Each villus contains a network of capillaries and a lymphatic vessel called a lacteal.
3. The presence of villi significantly enhances the absorptive capacity of the small intestine by increasing surface area.
4. Nutrients absorbed by the villi enter either the bloodstream through capillaries or the lymphatic system through lacteals.
5. Damage to villi, such as in celiac disease, can lead to malabsorption and nutritional deficiencies.

Review Questions

• What is the primary function of villi in the small intestine?
• How do microvilli contribute to the function of villi?
• What could be a consequence of damaged or flattened villi in terms of nutrient absorption?

Related terms

Microvilli: Tiny projections on epithelial cells that further increase surface area for absorption.

Lacteal: A lymphatic capillary found within each villus responsible for absorbing fats from digested food.

Celiac Disease: An autoimmune disorder where ingestion of gluten leads to damage in the small intestine's lining, affecting villi.