1.3.5

Exchange Surfaces

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Exchange Surfaces

Exchange surfaces are surfaces that are adapted to maximise the efficiency of gas and solute (a substance dissolved in a liquid) exchange across them. They have the following adaptations:

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Large surface area

  • A large surface area allows more of a substance to diffuse at the same time.
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Thin membrane

  • A thin membrane reduces the diffusion distance.
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Blood supply

  • Where substances are exchanged through blood in animals, exchange surfaces are densely packed with blood vessels:
    • These blood vessels replenish the blood supply to maintain a high concentration gradient by bringing in new blood as diffusion starts to even out the concentrations.
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Ventilation

  • In animals, if a gas is exchanged, the surface is ventilated (through breathing) to maintain a high concentration gradient and increase the rate of exchange.

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1Cell Biology

1.1What's in Cells?

1.2Cell Division

1.3Transport in Cells

2Organisation

2.1Principles of Organisation

2.2Enzymes

2.3Circulatory System

2.4Non-Communicable Diseases

2.5Plant Tissues, Organs & Systems

3Infection & Response

4Bioenergetics

5Homeostasis & Response

5.1Homeostasis

5.2The Human Nervous System

5.3Hormonal Coordination in Humans

5.4Plant Hormones

6Inheritance, Variation & Evolution

7Ecology

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