gas exchange in fish (module 3)

Question 1

how does fish allow gas exchange to occur

Answer 1

• fish opens mouth water passes over lamellae and oxygen diffuses into bloodstream
• waste products like CO2 diffuse into water and flow back out

Question 2

why is parallel flow not used in fish?

Answer 2

• blood and water flow in same direction so eventually reach equilibrium
• so concentration is not maintained along whole length of lamellae

Question 3

why does the countercurrent flow allow efficient gas exchange?

Answer 3

• blood and water flow in opposite directions along lamellae
• maintains concentration gradient
• along WHOLE LENGTH of lamellae

Question 4

how does ficks law apply to fish?

Answer 4

• large surface area provided by many gills which are covered by many gill lamellae
• countercurrent flow which maintains concentration gradient along lamellae
• short diffusion distance as epithelia and capillary walls one cell thick