BY2: Gas Exchange WJEC

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  • Created by: brittani
  • Created on: 18-03-14 18:03
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  • Gas Exchange
    • Humans
      • Alveoli are the gas exchange surfaces in humans
        • They are moist to allow oxygen to  diffuse through the cell wall
          • good bloody supply to keep the concentration gradient constant
        • The cell wall is only 1 cm thick for a short diffusion pathway
    • Fish
      • Water contains far less oxygen than air does
      • each gill is supported by the gill arch, and each gill has 2 rows of lamellae
        • once in water, the lamellae give large surface area for gas exchange
      • The gill plates are the  exchange surface in fish
      • Blood vessels bring de-oxygenated blood the gill plates,
        • Oxygen passes through the gill plates into the capillaries and carbon dioxide passes out into the water
      • counter current flow
        • blood in the capillaries flows in the opposite direction to the water flowing over the surface
        • they extract 80% of oxygen from the water
    • Insects
      • system  of tracheal tubes with spiracles open into a branching system that supply tissues with air
        • tracheoles attached to the tissues allow oxygen to diffuse straight into the tissues
        • the spiracles open and close so that it prevents water loss
    • Breathing
      • humans
        • diagphram goes down, intercostal muscles contract, pulling the ribcage upwards, allowing more air into the lungs
        • the internal intercostal muscles contract and the external intercostal muscles relax, diagphram moves upwards, forcing the outsdie of the lungs
      • fish
        • the mouth opens, the operculum closes, the floor of the mouth cavity lowers, the volume inside the mouth increase, water rushes into the mouth
        • the moth closes, the floor of the mouth cavity is raised, the volume inside the mouth decreases, and the operculum opens and water flows out
  • Alveoli are the gas exchange surfaces in humans
    • They are moist to allow oxygen to  diffuse through the cell wall
      • good bloody supply to keep the concentration gradient constant
    • The cell wall is only 1 cm thick for a short diffusion pathway
  • tracheoles attached to the tissues allow oxygen to diffuse straight into the tissues

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