Nutrient Absorption
Elementary School
Definition
The uptake of digested nutrients into the bloodstream, which in humans occurs mainly in the small intestine. Its lining is folded and covered in tiny projections that increase the surface area for absorbing nutrients efficiently.
Worked examples
After starch is broken into glucose in the small intestine, glucose molecules pass through the villi into capillaries and enter the bloodstream.
Villi increase surface area so glucose is absorbed efficiently into blood vessels.
Amino acids from digested protein are absorbed through the intestinal lining and transported via blood to cells throughout the body.
Nutrient absorption moves digested molecules from the gut into circulation for use by cells.
Common mistakes
- Nutrient absorption happens in the stomach → Nutrient absorption occurs mainly in the small intestine The stomach digests food; the small intestine's folded lining and villi are specialized for absorption.
- Villi absorb whole food particles like pieces of bread → Villi absorb small molecules like glucose and amino acids after digestion Only digested nutrients—broken-down molecules—can pass through the intestinal wall into blood.
- Absorption moves nutrients from blood into the intestine → Absorption moves nutrients from the intestine into the bloodstream Absorption is uptake from the gut lumen into circulation, not the reverse.
Where you'll use it next
You'll apply nutrient absorption when studying the full digestive system, comparing surface-area adaptations across organs, exploring disorders like celiac disease, and understanding how nutrients fuel cellular respiration and growth.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026