Gas Exchange in Fish

Question 1

What factors affect gas exchange?

Answer 1

1. The concentration gradient.
2. The surface area
3. The thickness of the membrane

Question 2

What is the structure of the gills of the fish?

Answer 2

The gills have filaments which increase the surface area. The filaments have lamellae that increase the surface area even more. The lamellae have a lot of capillaries that are one cell thick to decrease the diffusion distance.

Question 3

What is the counter-current system?

Answer 3

In the lamellae, the blood flows in one direction and the water passes over them in the opposite direction.

Question 4

What is the purpose of the counter-current system?

Answer 4

It maintains the steep concentration gradient between the water and blood, which increases the rate of diffusion in the gills.