Gas exchange in fish

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  • Created by: Laura
  • Created on: 02-05-14 14:49
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  • Gas exchange in fish
    • Fish have a waterproof and therefore gas tight outer covering. They also have a small surface area to volume ratio.
    • Structure of the gills
      • Gills are located within the body of the fish, behind the head.
      • They are made up of gill filaments
      • The gill filaments are stacked up in a pile. At right angle to the filaments are gill lamellae which increase the surface area of the gills
      • Water is taken in through the mouth and forced over the gills and out through an opening on each side of the body.
      • The flow of water over the gill lamellea and the flow of blood within them are in opposite directions known as the countercurrent flow.
    • Countercurrent exchange principle
      • Blood and water flow over the gill lamellea in the opposite direction
      • Blood that is already loaded with oxygen meets water that has its maximum concentration of oxygen . Therefore diffusion of oxygen from the water to the blood takes place
      • Blood with little or no oxygen in it meets water which has had most but not all of its oxygen removed. Again, diffusion from the water to the blood takes place


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