BRAINCAKEStructure of the Ileum
The walls of the ileum are folded with finger-like projections called villi. This increases the surface area for absorption.
The villi are about 1mm long. The villi contain muscle and are able to move and mix the contents of the ileum.
The villi have thin walls lined with epithelial cells which surround a network of capillaries. The rich blood supply removes absorbed substances away from the ileum maintaining the diffusion gradient.
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Key terms in this lesson
- diffusion
- The net passive movement of molecules or ions from a region of higher concentration to a region of lower concentration, down a concentration gradient.
More in Digestion
- The Digestive System
- Carbohydrate Digestion
- Lipid Digestion
- Protein Digestion
- Absorption of Amino Acids
- Absorption of Monosaccharides
- Absorption of Triglycerides
- Absorption of Fatty Acids
All 10 lessons in Digestion · All AQA AS-level Biology topics