# Gaseous Exchange in Bony Fish

HideShow resource information
Why do fish need a different gaseous exchange surfaces to mammals or insects?
They don't have to prevent water loss, they live in water but it is so much denser and viscous, water has less oxygen content, slower rate of diffusion, would take a lot of energy to breathe in the water etc
1 of 9
Gills
Water flows over the gills and it takes O2 out and expels CO2, Large SA, good blood supply, thin layers, protected by operculum (bony flap) and it maintains flow of water,
2 of 9
Gill Filaments
Folds in the gills, increasing SA
3 of 9
Gill Lamellae
Protrusions in the gill filaments, adding even more SA
4 of 9
Bucal Cavity
The mouth of the fish
5 of 9
Describe how water flows over the gills
When the fish swims, it opens it nought and water can pass through and out of the gills and the operculum, they have to use ram ventilation when they stop swimming
6 of 9
Describe ram ventilation
The floor of bucal cavity lowers as mouth opened, increasing volume in bucal cavity and lowers the pressure so water moves into the BC, opercular cavity containing gills is closed, water moves into opercular cavity, mouth closes, forcing water out
7 of 9
Name the 2 extra adaptions bony fish have to increases effectivity of gaseous exchange
Filaments overlap (increasing the resistance of water, more time for GE) Countercurrent flow of water and blood (they move in opposite directions, increases diffusion rate)
8 of 9
Explain countercurrent flow
The water moving over the gills and the blood in the filaments move in opposite directions to each other, maintains a steep conc grad, more gaseous exchange can take place, continuous net movement of oxygen going into blood from water
9 of 9

## Other cards in this set

### Card 2

Gills

#### Back

Water flows over the gills and it takes O2 out and expels CO2, Large SA, good blood supply, thin layers, protected by operculum (bony flap) and it maintains flow of water,

Gill Filaments

Gill Lamellae

Bucal Cavity