Which intestinal features increase absorptive surface area and what is the role of villi and microvilli?

• A. Villi and microvilli increase surface area; enterocytes absorb nutrients via transporters; lacteals absorb lipids; capillaries absorb monosaccharides and amino acids.
• B. Intestinal crypts increase surface area; goblet cells absorb nutrients.
• C. Microvilli reduce surface area; enterocytes secrete hormones.
• D. Villi do not affect absorption; microvilli uptake water.

Answer: (A)

Absorptive surface area is expanded by finger-like villi and their even tinier extensions, microvilli, forming a brush border. Villi provide a large surface for nutrient contact and contain a capillary bed plus a central lacteal; nutrients crossing the epithelium are then taken up into these vessels. Monosaccharides and amino acids are absorbed into the capillaries and enter the hepatic portal circulation, while lipids are packaged into chylomicrons and absorbed into the lacteals of the lymphatic system. Microvilli, densely packed on the surface of enterocytes, further increase surface area and host brush border enzymes and transporters that finish the digestion and uptake of nutrients like glucose, galactose, and amino acids. In short, villi and microvilli work together to maximize contact with chyme and route nutrients to the correct absorption pathways.