Villi and microvilli
Glucose absorbed through walls of small intestine.
Walls are folded, possess finger-like projections called villi.
Small intestines have thin walls, lined with epithelial cells, otherside - rich network of blood capillaries.
Villi = increase surface area therefore accelerate rate of absorption.
Part of specialised exchange surface between lumen of small intestine and blood vessels, adapted for absorption of production of digestion.
- Increase surface area for diffusion.
- V. thin walled = reduced diffusion path.
- Able to move = maintain diffusion gradient.
- Well supplied with blood vessels = maintain diffusion gradient.
Epithelial cells possess microvilli = fingerlike projections on cell surface membrane - collectively brush border.
Role of diffusion in absorption
Carbohydrates being digested continuously = greater concentratino of glucose within lumen of small intestine than in blood = concentration gradient.