Gas Exchange in Fish Flashcards
What is the specialised gas exchange surface in fish?
The gills
What is the outer coating on fish?
Waterproof and gas-tight
Why do fish need a specialised gas exchange system?
Because their body is relatively large and they have a relatively small surface area to volume ratio
Where are the gills located?
Inside the body of the fish, behind the head
What are the gills made of?
Gill filaments
How are gill filaments arranged?
They are stacked in a pile
How are gill lamellae arranged?
At right angles to the filaments
What do the gill lamellae do?
Increase the surface area of the gills
How does water pass over the gills?
Water is taken in through the mouth and forced over the gills, it then leaves through an opening on each side of the body
How is the flow of water and the flow of blood a countercurrent flow?
The water flows in an opposite direction to the blood over the gill lamellae
Why is the flow of blood and water is a fish counter current?
To maximise gas exchange
What does the counter current flow allow for?
- oxygenated blood to pass over deoxygenated water
- deoxygenated blood to pass over oxygenated water
- this allows a diffusion gradient to be maintained
What happens as a result of counter current flow?
A diffusion gradient is maintained for oxygen across the gill lamellae because of this about 80% of oxygen that passes over the gills is absorbed
What is parallel flow?
Flow of oxygen and blood in the same direction
