3 gas exchange in fish

where does gas exchange occur in fish?

in the lamella in the gills

what special adaptation do fish have to maintain the concentration gradient to enable diffusion?

countercurrent flow

what’s the structure of the gills?

four layers of gills on both sides of the head. the gills are made up of stacks of gill filaments. each gill filament is covered in gill lamellae, positioned at right angles to the filament. this creates a large surface area

what happens when fish open their mouths?

water rushes in and over the gills and then out through a hole in the side of their head

how does a fish have a short diffusion distance?

due to a capillary network in every lamellae and very thin gill lamellae

how’s the concentration gradient maintained?

by the countercurrent flow mechanism

what’s the countercurrent flow mechanism?

when the water flows over the gills in the opposite direction to the flow of blood in the capillaries

what’s the countercurrent flow mechanism for?

ensures equilibrium is never reached and that a diffusion gradient is maintained across the entire entire length of the gill lamellae