gas exchange in fish

Question 1

adaptations of the material of outside of fish

Answer 1

waterproof + gas-tight outside covering

Question 2

where are the gills found

Answer 2

behind the head of the fish

Question 3

what are the two parts of the gills and what are the structures of them

Answer 3

gill filaments - stacked in a pile
gill lamellae - at right angles to filaments increasing SA

Question 4

describe what the counter current mechanism is

Answer 4

blood flow in lamellae and water flow over lamellae are opposite direction

Question 5

tell me how the counter current mechanism helps with gas exchange

Answer 5

blood with high O2 meets water with high O2
same for low O2
maintaining diffusion gradient of 80%
Maintaining concentration gradient across whole length of gills

Question 6

name the parts of a fish involved in the ventilation mechanism

Answer 6

buccal cavity
opercular cavity
gill cavity
operculum

Question 7

what happens when fish opens its mouth in ventilation

Answer 7

floor of buccal cavity is lowered
causing volume inside buccal cavity to increase
decreasing pressure in cavity

Question 8

what happens once water enters fishes mouth due to pressure difference

Answer 8

fish raises floor of buccal cavity to close its mouth
increasing pressure in buccal cavity

Question 9

what happens once fish closes its mouth

Answer 9

water flows from buccal cavity (high pressure) to the gill cavity (low pressure)

Question 10

what happens when water enters gill cavity

Answer 10

pressure builds up in gill cavity
causing operculum to open and water to leave fish

Question 11

describe the operculum

Answer 11

flap of tissue covering gills

Question 12

what happens once water has left operculum

Answer 12

operculum is pulled shut when floor of buccal cavity is lowered at start of next cycle starts