Gas Exchange In Fish

Question 1

What are the gills made up of

Answer 1

Gill filaments

Question 2

What do gill lamellae do

Answer 2

Increase SA of gills

Question 3

What is the countercurrent exchange system

Answer 3

Blood and the water that flow over the gill lamellae do so in opposite directions

Question 4

Describe the counter current system

Answer 4

Water containing oxygen enters the fish through its mouth passes out for the grills

Each gill is made of lots of thin plates called Gill filaments, which give a big surface area for exchange of gases

The girls filaments are covered in lots of tiny structures called lamallae, which increases the surface area even more

The lamellae has lots of blood capillaries and a thin surface layer of cells to speed up diffusion

Blood flows through the lamellae in one direction and water flows over in the opposite direction. This is called a counter current system. It maintains a large concentration gradient between the water and the blood. The concentration of oxygen in the water is always higher than that in the blood, so as much oxygen as possible diffuses from the water into the blood

Question 5

What percent of oxygen available in the water is absorbed into the blood of the fish

Answer 5

80%

Question 6

Outline why countercurrent flow is an efficient means of exchanging gases across the gills of fish

Answer 6

Because a steady diffusion gradient is maintained over the whole length of the gill lamellae. Therefore more oxygen diffuses from the water into the blood