Zusammenfassung der Ressource
How the small
intestine is adapted for
its job.
- Very long with many folds.
- This gives plenty of time for digestion to be
completed and for nutrients to be absorbed.
- About 5m long in an adult.
- Has villi
- Every villus has cells with even
smaller projections called microvilli.
- Gives inner surface of the small intestine a very large surface area
- Food can be absorbed more quickly.
- Contain blood capillaries (good blood supply).
- Only one cell thick.
- The digested food can easily cross the wall to
reach the blood capillaries. Shorter diffusion path.
- Concentration gradient maintained-helps diffusion.
- Peristalsis constantly brings in a fresh supply of food, therefore
high concentration gradient in the gut lumen.
- Blood is flowing, constantly taking away the absorbed molecules therefore ensuring a low
concentration here.