How does the structure of the intestinal villus support absorption?

How does the structure of the intestinal villus support absorption?

• A. Villi and microvilli decrease surface area; capillaries absent
• B. Villi lack brush border enzymes
• C. Villi and microvilli increase surface area; rich capillary network and lacteals; brush border enzymes present
• D. Villi are only in the stomach

Answer: (C)

The main idea is that absorption is boosted by structure that both increases contact with nutrients and provides efficient pathways away from the gut lumen. The intestinal villus, with its many tiny projections called microvilli, greatly enlarges the surface area available for nutrient uptake. Inside each villus is a rich capillary network to carry sugars and amino acids into the bloodstream, plus a lacteal lymphatic vessel to transport absorbed fats. The brush border enzymes on the microvilli finish digestion right at the site, so nutrients are ready for transport immediately. That combination—more surface area, vessels for circulation and lymphatic transport, and enzymes right at the border—explains why this structure supports efficient absorption. The other ideas don’t fit: decreasing surface area would slow absorption, lacking brush border enzymes isn’t true, and villi aren’t located in the stomach.

The main idea is that absorption is boosted by structure that both increases contact with nutrients and provides efficient pathways away from the gut lumen. The intestinal villus, with its many tiny projections called microvilli, greatly enlarges the surface area available for nutrient uptake. Inside each villus is a rich capillary network to carry sugars and amino acids into the bloodstream, plus a lacteal lymphatic vessel to transport absorbed fats. The brush border enzymes on the microvilli finish digestion right at the site, so nutrients are ready for transport immediately. That combination—more surface area, vessels for circulation and lymphatic transport, and enzymes right at the border—explains why this structure supports efficient absorption. The other ideas don’t fit: decreasing surface area would slow absorption, lacking brush border enzymes isn’t true, and villi aren’t located in the stomach.