Gas Exchange In Fish

Question 1

What are some features of the gill’s structure?

Answer 1

• series of bony gill arches with 2 stacks of gill filaments
• gill filaments have very thin lamellae in protruding rows
• each lamellae has a network of capillaries covered by a single layer of epithelial cells
• very delicate so protected by the operculum - bony plate

Question 2

What is buccal pumping?

Answer 2

The fish coordinate the opening of the operculum vents with the closing of the buccal cavity
When the fish open the buccal cavity and close the operculum vents, water is drawn in to be pumped over the gills

Question 3

What is buccal pumping for?

Answer 3

Maintaining a strong diffusion gradient for efficient gas exchange

Question 4

What is the countercurrent flow?

Answer 4

The orientation of gill filaments and lamellae means that water flowing over them moves countercurrent to the blood flow though the capillaries which ensures maximum efficiency of gas exchange at the gills

Question 5

What happens when the blood has low oxygen levels in the countercurrent flow?

Answer 5

Flows past water with some oxygen which creates a diffusion gradient so oxygen still diffuses into the blood

Question 6

What happens when the blood is partially saturated in the countercurrent flow?

Answer 6

Flows past water loaded with oxygen so diffusion still occurs down the concentration gradient

Question 7

What would happen if fish used parallel flow instead?

Answer 7

Would result in both water and capillaries containing equal amounts of oxygen since regular diffusion would happen which is less effective