gas exchange in fish

Question 1

where are the gills located

Answer 1

behind the fish’s head

Question 2

what are gills made up of

Answer 2

gill filaments which are attached to the gill bar. at right angle to the gill filaments are the gill lamellae which increase the surface area of the gills.

Question 3

what is counter current flow

Answer 3

the flow of water over the gill lamellae and the flow of blood within them are in opposite directions.

Question 4

what does counter current flow ensure

Answer 4

it ensures that an equilibrium is not reached and that a diffusion gradient is maintained across the entire length of the gill filament. (almost all of the oxygen from the water is diffused into the blood)

Question 5

what is parallel flow (co-current flow)

Answer 5

a diffusion gradient is maintained for only half the distance across the lamellae. (only 50% of oxygen is diffused into the blood)

Question 6

what happens when a fish breaths

Answer 6

as a fish opens its mouth they gulp water which they then pass over the gills