Anyone know a good and easy description of fish ventilation?

Question

I have my Biology AS level mock tomorrow, and this is the thing I find most confusing!

But more detail than just gills!

Specifically 'Ventilating the gills'

And thanks, but I do understand countercurrent flow, its just the process of ventilation and the movement of water through the buccal cavity and out of the operculum valve, and presure and volume changes that is confusing me!

Answer 1

Ventilation, by definition, is the flow of the respiratory medium (in the case of fish, water) over the respiratory surface (gills). Thus, anything that would increase the rate of flow would increase ventilation. Ventilation in fish is made more efficient by the counter-current exchange mechanism.

Answer 2

Bony fish respirate through a coutercurrent flow. Deoxygenated blood flows one way, oxygenated blood flows the other. It maintains a concentration gradient. The gills allow this due to the fact that they have a large surface area, high blood flow to the gills and they have short diffusion distances.

Hope this helps

Answer 3

Gills