Which surface feature increases the absorptive surface area on the apical surface of small intestinal cells?

Which surface feature increases the absorptive surface area on the apical surface of small intestinal cells?

• A. Desmosomes
• B. Microvilli (brush border)
• C. Cilia
• D. Tight junctions

Answer: (B)

Microvilli on the apical surface of small intestinal cells are the key feature that boosts absorptive surface area. These tiny projections, together called the brush border, significantly expand the area available for nutrient transporters and digestive enzymes right where absorption happens. This arrangement allows more efficient uptake of sugars, amino acids, and fats, with brush border enzymes like lactase, sucrase, maltase, and peptide hydrolases performing final digestion at the site of absorption. Other surface features aren’t about increasing surface area: desmosomes and tight junctions are for cell–cell adhesion and barrier function, and cilia are motile extensions used for movement in other tissues, not the intestinal absorptive surface.

Microvilli on the apical surface of small intestinal cells are the key feature that boosts absorptive surface area. These tiny projections, together called the brush border, significantly expand the area available for nutrient transporters and digestive enzymes right where absorption happens. This arrangement allows more efficient uptake of sugars, amino acids, and fats, with brush border enzymes like lactase, sucrase, maltase, and peptide hydrolases performing final digestion at the site of absorption. Other surface features aren’t about increasing surface area: desmosomes and tight junctions are for cell–cell adhesion and barrier function, and cilia are motile extensions used for movement in other tissues, not the intestinal absorptive surface.