What increases surface area of the small intestine?

• A. Goblet cells
• B. Intestinal villi
• C. Duodenum
• D. Ileocecal valve

Answer: (B)

Increasing absorptive surface area in the small intestine is achieved by specialized mucosal structures. The intestinal villi are finger-like projections that extend into the lumen, dramatically expanding the area available for nutrient uptake. Each villus contains a rich capillary network and a central lacteal, so absorbed nutrients are quickly carried away. On the surface of the epithelial cells lining each villus are microvilli, tiny projections that form the brush border and multiply membrane area even further. This combination of folds, villi, and microvilli provides a huge boost to surface area and enhances nutrient absorption. Goblet cells secrete mucus and don’t contribute to increasing surface area; the duodenum is a section of the small intestine, and the ileocecal valve is a sphincter that controls flow, not a mechanism to boost surface area.