Fish

• Picture 


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• Pathway 


  • Buccal cavity
  • Gill
  • Gill filaments
  • Lamellae
  • Opperculum
• Lamellae


  • A single layer of flattened cells on the gill filaments
  • Increase surface area
  • Short diffusion pathway
• Gill filaments


  • Stacks of two thin plates on each gill that increase surface area
• Opperculum


  • Muscle that protects the gills, opens when water is pushed out of the gills 
• Buccal cavity


  • The mouth of the fish where water enters
• Counter current


  • Water flows past the lamellae in the opposite direction to the blood flow, this is called counter current
  • This maintains a constant concentration gradient for O2 to keep diffusing into the blood and CO2 out