Gas Exchange In Fish: Gills

Question 1

What is the specialised system for gas exchange?

Answer 1

The gils

Question 2

What is the site of gas exchange in fish?

Answer 2

The capillaries in the lamellae

Question 3

Movement of O2 through the fish

Answer 3

1) Water carrying oxygen moves i. through the mouth
2) Gills have finger-like projections called gill filaments where oxygen diffuses to down a concentration gradient
3) Each filament has many lamellae
4) Lamellae contain capillaries (site of gas exchange)
5) Water carrying oxygen passes through the lamellae, most of the O2 is removed and enters the capillaries
6) Water containing little oxygen leaves through the gill opening called an operculum

Question 4

Adaptations of gills for efficient gas exchange

Answer 4

•Many gill filaments containing many lamellae together provide a large surface area for diffusion
•Thin epithelium of the lamellae for a short diffusion distance between water and blood
•Lamellae positioned at right angles allowing water to pass through the gills

Question 5

What is the countercurrent flow?

Answer 5

The position of gill filaments and their lamellae flow in opposite directions

Question 6

What is the benefit of the countercurrent flow through gills?

Answer 6

Massively increases fish’s ability to absorb oxygen from water as a diffusion gradient is maintained across the entire gill, decreasing the chances of reaching equilibrium