Fish Gas Exchange

• What are the main components of fish gills?

  Gills are made up of gill filaments covered with lamellae.
• How do lamellae contribute to gas exchange in fish gills?

  Lamellae increase the surface area of gills, facilitating gas exchange.
• What features of lamellae enhance diffusion in fish gills?

  Lamellae have many blood capillaries and a thin surface layer of cells.
• How does blood flow in fish gills maintain the concentration gradient?

  Blood flow maintains the concentration gradient by continuously removing oxygen from the lamellae.
• What is the purpose of the counter-current flow in fish gills?

  Counter-current flow maintains the concentration gradient between water and blood.
• How does counter-current flow ensure maximum oxygen absorption in fish gills?

  It ensures that blood always has a higher oxygen concentration than the water flowing past it.
• What is the ventilation mechanism in fish?


  • Constantly pushes water over the gills
  • Ensures a supply of oxygen-rich water
  • Maintains the concentration gradient for gas exchange
• What happens when a fish opens its mouth during ventilation?


  The floor of the buccal cavity lowers, increasing the volume and decreasing the pressure inside.
• What causes water to flow into the buccal cavity of a fish?

  Water flows into the buccal cavity due to higher pressure outside the mouth compared to inside.
• What occurs after the fish closes its mouth during the ventilation process?

  The floor of the buccal cavity is raised, increasing pressure and forcing water into the gill cavity.
• What happens when water enters the gill cavity?

  Pressure builds up in the gill cavity, forcing the operculum open and allowing water to exit.
• What role does the operculum play in fish ventilation?

  The operculum is a flap of tissue that covers the gills and opens to allow water to exit.
• What happens to the operculum during the next ventilation cycle?

  The operculum is pulled shut when the floor of the buccal cavity is lowered.
• How does an increase in water temperature affect oxygen concentration for fish?

  An increase in water temperature leads to a lower concentration of oxygen.
• What do fish do in response to a decrease in oxygen concentration due to higher water temperatures?

  Fish increase their ventilation rate to maintain oxygen flow and diffusion.
• What is the advantage of increasing ventilation rate when oxygen concentration falls?

  It maintains the flow of oxygen and supports respiration despite lower oxygen levels.