Small Intestine
Biology: Cambridge International GCSE Supplement, topic 7.5.1
Small Intestine
The small intestine is a long, coiled organ in the human digestive system. After food is broken down in the stomach, the small intestine absorbs nutrients into the bloodstream.
Absorption of nutrients
- The small intestine is the main site of absorption of nutrients.
- The inner surface has tiny, finger-like projections called villi to increase surface area, speeding up absorption.
- Nutrients absorbed include:
- Glucose and amino acids → into the blood
- Fatty acids and glycerol → into the lymph
Absorption of water
- Most of the body’s water is absorbed in the small intestine.
- This water comes from the liquids we drink and the water content of our food.
- Some additional water absorption also happens in the colon (large intestine) as the final stage of digestion.
Test yourself on Small Intestine
What is the primary role of the small intestine?
After food is broken down in the stomach, where does the small intestine absorb nutrients into?