Gss Exchange In Fish Flashcards
What are the gas exchange organs in fish?
Gills, which are located between fishes buccal cavity and operculum cavity, and a chamber at the side of their mouth called the operculum.
How does the gas exchange happen?
Oxygen passes from water into the blood at the gills, carbon dioxide also removed, as blood containing a high concentration of CO2 goes to the gills, and co2 diffuses out by conc gradient.
How do fish inhale?
The mouth opens
Operculum closes, opening at back of pharynx
Floor of mouth cavity is lowered
Volume of mouth cavity increases and pressure falls
Water pulled in
How do fish exhale?
Mouth closes
Floor of mouth cavity is raised
Volume of mouth cavity decreases and pressure increases
Water flows across gills
Operculum forces open
What are gills composed of?
2 rows of filaments, increasing SA
Each gill has many filaments which are covered in many tissue flaps called gill rakers.
What do gill plates do?
Further increase SA and ensure diffusion distance is small between blood and water as they are thin.
Gill played contain capillaries which have blood flowing opposite direction to water
What is counter current flow?
Blood flows in opposite direction to water in counter current exchange.
This ensures maximum exchange of oxygen and CO2 across whole gill plate.
It is more efficient than parallel flow as blood always meets with water with a higher % saturation of zudem so diffusion is faster as no equilibrium is reached
See diagram p28
What are 3 parts of gill?
Gill filaments
Gill arch
Gill rakers
What do gill filaments aka lamellae do
Provide large SA, filled with blood, short diffusion path
What does gill arch do?
Has bony structure to support filaments + rakers
What does gill rakers do?
Trap pray + debris and filters water
