GAS EXCHANGE IN FISH

Question 1

what do bony fish have

Answer 1

waterproof scales
small SA:V

Question 2

describe gills in fish

Answer 2

gills are made from gill filaments (thin plates) that are stacked up
gill lamellae ( on the upper and lower surfaces of the filaments) are perpendicular to the filaments
as water passes through the gills - gas exchange occurs at the lamellae

Question 3

describe the adaptations for gas exchange in fish

Answer 3

1. many gill filaments / lamellae means a large total surface area
2. single layer of thin epithelial cells so a short diffusion pathway
3. dense network of capillaries underneath also providing a short pathway
4. fish pushes water over the gills providing constant ventilation
5. counter current system maintains conc gradient

Question 4

what is the counter current system

Answer 4

flow of blood and water over the lamellae is in opposite directions

Question 5

why is parallel flow bad

Answer 5

the diffusion gradient is only maintained for half the distance of the lamellae so only 50% of oxygen diffuses in