Which feature increases the efficiency of nutrient absorption?

Which feature increases the efficiency of nutrient absorption?

• A. The pH of the large intestine
• B. The rate of gastric emptying
• C. The surface area of the small intestine
• D. The thickness of the stomach wall

Answer: (C)

Maximizing contact area between the nutrient-containing fluid and the absorptive surface of the gut is what boosts how efficiently nutrients are absorbed. The small intestine achieves this with folds called plicae circulares, finger-like villi, and tiny microvilli on the surface of each absorptive cell. This combination expands the surface area dramatically—hundreds of square meters in total—so more nutrients can interact with transport proteins and move into the bloodstream. Other factors don’t raise the absorption capacity itself. The pH of the large intestine affects microbial activity more than the amount absorbed. The rate of gastric emptying changes how quickly contents reach the absorptive surface, influencing timing and concentration but not the overall capacity for absorption. The thickness of the stomach wall doesn’t alter the small intestine’s ability to absorb nutrients. So, the feature that increases absorption efficiency is the large surface area of the small intestine.

Maximizing contact area between the nutrient-containing fluid and the absorptive surface of the gut is what boosts how efficiently nutrients are absorbed. The small intestine achieves this with folds called plicae circulares, finger-like villi, and tiny microvilli on the surface of each absorptive cell. This combination expands the surface area dramatically—hundreds of square meters in total—so more nutrients can interact with transport proteins and move into the bloodstream.

Other factors don’t raise the absorption capacity itself. The pH of the large intestine affects microbial activity more than the amount absorbed. The rate of gastric emptying changes how quickly contents reach the absorptive surface, influencing timing and concentration but not the overall capacity for absorption. The thickness of the stomach wall doesn’t alter the small intestine’s ability to absorb nutrients. So, the feature that increases absorption efficiency is the large surface area of the small intestine.