gas exchange in fish

• what problems are caused by living in water

  water contains less oxygen then air , diffusion is slower in water and water is a dense medium so air doesn't flow as freely
• what are the two types of fish

  Boney fish and cartilagenous fish
• What is an amphibian?


  a vertebrate that is ectothermic and spends its early life in water
• what is meant by ectothermic


  these are animals whos temperature that depends on external sources
• what is an aquatic animal


  an animal that lives in water
• what is an example of a cartilaginous fish


  a shark
• describe the skeleton in a cartilaginous fish


  it is entirely made of cartilage
• do all cartilaginous fish live in sea water


  no but most of them do
• describe the gills on a cartilaginous fish


  they have five gill clefts on each side of the body just behind the head
• describe the path taken by water in a cartilaginous fish


  the water is taken into the mouth and is forced out through the gill slits when the flood of the mouth is raised
• what type of blood flow takes place in a cartilaginous fish parallel or counter current flow


  parallel flow
• describe parallel flow in cartilaginous fish


  blood in the gill capillaries circulates in the same direction as water flows over the gills
• describe the skeleton in a bony fish


  entirely made of bone
• describe the gills in a bony fish


  they are covered with a flap called the operculum
• what types of water do bony fish inhabit


  both fresh and sea water
• what type of blood flow takes place in a bony fish parallel or counter current flow


  counter current flow
• describe counter current flow in bony fish


  the blood circulates in the opposite direction as the water flows over the whole length of the gills
• what type of flow across the gill maintains a concentration gradient


  counter current flow
• during parallel flow what happens to diffusion along the gill lamellae


  once it reaches equilibrium diffusion will stop
• during counter-current flow what happens to diffusion along the gill lamellae


  a concentration gradient is maintained and diffusion will continue to take place
• what is more efficient parallel or counter current flow and why


  parallel due to the steeper concentration gradient at eh beginning of the gas exchange