Ventelation in Fish

• Structure and components of Gills

  • Structure of fish gills in bony fish:
  • Series of gills on each side of the head
  • Each gill arch is attached to two stacks of filaments
  • On the surface of each filament, there are rows of lamellae
  • The lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries
• What is the system of blood and water in the gills?

  Counter-Current
• What is a counter current system?

  When blood flow is in the opposite direction to the flow of water
• Why is the counter current system important?

  It ensures the concentration gradient is maintained along the whole length of the capillary
• Label the diagram

  A) Gill Arches

  B) Fillaments

  
• Label the diagram

  A) Deoxygenated blood

  B) Oxygenated blood

  C) Flow of Water

  D) Lamelles

  E) Fillaments

  F) Blood flow opposite to water flow

  
• How does the ventelation sytem work?

  Constantly pushes water over the surface of the gills and ensures they are constantly supplied with water rich in oxygen
• What does constant supply of water over the gills maintain?

  The concentration gradient
• What happens when the mouth opens?

  Causes the fish to lower the floor of the buccal cavity
• What does lowering the buccal cavity cause?

  Causes the volume inside the buccal cavity to increase, which causes a decrease in pressure within the cavity
• After the buccal cavity is filled with water the fish raises the floor of the buccal cavity. What does this cause?

   An increase in the pressure within the buccal cavity
• • Water flows from the buccal cavity (high pressure) into the gill cavity (low pressure)
• • As water enters pressure begins to build up in the gill cavity and causes the operculum (a flap of tissue covering the gills) to be forced open and water to exit the fish
• • The operculum is pulled shut when the floor of the buccal cavity is lowered at the start of the next cycle
• Label the diagram

  A) Mouth open

  B) Floor of the buccal cavity lowers

  C) Water enters due to the pressure difference

  D) Buccal cavity

  E) Gill cavity

  F) Operculum

  G) Opercular Cavity

  
• Label the diagram

  A) Mouth closes

  B) Floor of the buccal cavity raises increasing pressure

  C) Water is pushed over the gills

  D) Increased pressure causes water to be pushed out