Exchange surfaces
- Created by: Kittykatty2000
- Created on: 26-03-17 14:59
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Features of specialised exchange surface:
- Large surface area to volume ratio - increases rate of exchange
- Very thin - short diffusion distance and therefore materials cross the exchange surface rapidly
- Selectively permeable - allow selected materials to cross
- Movement of the environmental medium - maintain a diffusion gradient
- A transport system - to ensure the movement of the internal medium
- Being thin, specialised exchange surfaces are easily damaged and dehydrated.
- They are therefore often located inside an organism
- When an exchange surface is located inside the body, the organism needs to have a means of moving the external medium over the surface
Things that need to be interchanged between an organism and its environment:
- Heat
- Excretory products
- Nutrients
- Respiratory gases
Except for heat, these exchanges can take place in two ways:
- Passively (no metabolic energy is required) through diffusion and osmosis
- Actively (metabolic energy required) through active transport
Small intestine -
- Large SA:VOL - (microvilli-folds) for…
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