Exchange Surfaces

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  • Created by: Katherine
  • Created on: 05-04-13 21:19

Exchange Surfaces

Exchange surfaces are adapted to maximise effectiveness.

An effecive echange surface allows enough of a substance to pass through it.

The size and complexity of an organism increases the difficulty of exchanging materials.

The effectiveness of an exchange surface is increased by:

  • Being thin, to provide a short diffusion path
  • Having a large surface area, so lots of a substance can pass through at once
  • Animals have lots of blood vessels, so there is an efficeint blood supply
  • Gas exchange surfaces in animals are often well ventilated 
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Exchange Surfaces in Humans

Gas Exchange in Humans:

  • The surface are of the lungs is increased by millions of air sacs called alveoli
  • The alveoli are specialised to maximise the difusion of oxygen and carbon dioxide.
  • They have:
    • An ernormous surface area
    • A moist lining for dissolving gases
    • Very thin walls
    • A good blood supply

Solute Excahnge in Humans: 

  • The surface area of the small intestine is increased by villi.
  • The villi porvides a large surface area with an extensive network of capillaries to absorb the products of digestions efficiently, by diffuision and active transport.
  • They have:
    • A single layer of surface cells
    • A very good blood supply to assist quick absorbtion. 
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