B3 Exchange in the gut
- Food digested into small soluble molecules. Small intestines- solutes absorbed into the blood- Villi line the inner surface of small intestine and exchange surface for food molecules.
- Villi- greatly increase surface area. Walls are very thin and many capillaries are close to the wall
- Active Transport- allows cells to take in substances against concentration gradient.
- It uses energy from respiration. Ions from dilute solutions, like sugar- can be absorbed by active transport.
- Osmosis- is the movement of water. It is the diffusion of water across a particaly permeable membrane. It moves water from a high water concentration to a region of lower water concentration.
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