ventilation in fish

Question 1

why wont mammalian ventilation work in fish

Answer 1

water is 1000x denser than air, 100x more viscous than air, lower O2 content than air

Question 2

function of gills

Answer 2

maintain water flow over gills
large SA + good blood supply + thin layers

Question 3

structure of gills

Answer 3

gill cavity has 4 gills
1 gill = 1 gill arch, 2 gill plates

1 gill plate = a stack of gill filament

each gill filament has many gill lamellae

Question 4

what is buccal cavity

Answer 4

the mouth

Question 5

inspiration in fish

Answer 5

opens mouth, lowers buccal cavity, volume increases, pressure decreases
pressure higher outside, water flows in bc down concentration gradient
operculum expands, pressure decrease

Question 6

expiration in fish

Answer 6

mouth close, raise buccal cavity, decreases volume, increase pressure
pressure higher in bc than in gill cavity, water flows in gill cavity, pressure increase, force operculum open, water moves over gills

Question 7

how is gas exchange effective in water

Answer 7

tips of adjacent gills overlap - increase resistance of water flow, increase time for gas exchange

countercurrent flow - maintains steep concentration gradient so more gas exchange takes place

Question 8

what is countercurrent system

Answer 8

blood and water in opposite direction
steep concentration gradient maintain
higher level of oxygen saturation in blood achieved