Cards (7)

  • fish can extract as much as 80% of available oxygen passing through it's gills
  • features of gills
    • large surface area
    • short diffusion distance
    • high concentration gradient
  • gills
    • 4 gill arches on either side of fish
    • supports the gills
    • lies between the mouth cavity and the opercular flaps
    • gill lamella increase surface area
  • inspiration
    • floor of buccal cavity is lowered
    • opercular valve closed
    • water enters through mouth over the gills
  • expiration
    • mouth closes
    • buccal cavity raised
    • water is forced over open opercular valve
  • counter current exchange
    • blood and water flow over the gill lamella in opposite direction
    • relatively constant rate of diffusion
    • favour the diffusion of oxygen from water into blood all the way across the lamellae
    • almost all oxygen is absorbed
  • parallel flow system:
    • blood and water move in the same direction
    • only about 50% of oxygen is absorbed
    • favours diffusion of oxygen into blood for only part of the gill lamellae