Gas Exchange in Fish

• Why have bony fish evolved a specialized gas exchange system?

  To extract maximum oxygen from water
• What is a significant issue bony fish face regarding gas exchange?

  They have a low surface area to volume ratio
• How do bony fish obtain oxygen?

  From the water passing over thier gills
• What is the role of the operculum in bony fish?

  It covers the gills and aids in water flow
• What happens to oxygen in the gills of bony fish?

  Oxygen diffuses from water into the blood
• What are gill lamellae also called?

  Gill plates
• Why are gill lamellae adapted for efficient gas diffusion?

  They have a massive surface area
• What is the advantage of the counter current exchange system in bony fish?

  It maintains a steep concentration gradient
• How does the flow of blood differ from the flow of water in bony fish?

  Blood flows opposite to water flow
• What happens when blood and water flow in the same direction?

  Equilibrium is reached, stopping diffusion
• What percentage of oxygen can diffuse into the blood with counter current flow?

  Up to 80%
• How do bony fish maintain constant water flow through their gas exchange system?

  By using a buccal cavity mechanism
• What happens when a bony fish opens its mouth?

  Water flows into the buccal cavity
• What occurs when the operculum is shut?

  Pressure in the opercular cavity falls
• What happens when the fish closes its mouth and opens its operculum?

  Water is forced out of the operculum
• What are the key components of the gas exchange system in bony fish?

  • Operculum
  • Opercular cavity
  • Gills
  • Gill arches
  • Gill filaments
  • Gill lamellae
• What are the adaptations of gill lamellae for gas exchange?

  • Massive surface area
  • Short diffusion distance
  • Extensive network of blood capillaries