Gas exchange in fish
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Three parts of the fish gills
Gill arch , gill filaments and lamellae
Where does diffusion happen in fish
Specifically in the lamellae
How does oxygen diffuse into a fish
Fish opens mouth to let water in. The water contains a higher concentration of oxygen compared to the capillaries deoxygenated blood. Oxygen from the water diffuses into the capillaries down its concentration gradient
How does carbon dioxide diffuse out of a fish
Carbon dioxide diffuses into the water because fish is constantly respiring so the concentration of carbon dioxide is higher in the blood than in the water
Three adaptation of fish gills that increase gas exchange
Large SA:V Ratio Short diffusion distance Counter-current flow
Counter-current flow
The water that is flowing in the the fish flows in opposite direction to the blood. Blood is never 100% oxygenated as blood is always passing water with higher oxygen concentration. This ensures a concentration gradient is maintained across the ENTIRE lamella. (Dexoygenated blood is constantly passing oxygenated water)
Large SA:V ratio
Many long and thin gill filaments covered in many lamellae (capillaries) The more gill filaments and lamellae the larger SA:V ratio the increased rate of gas exchange
Short diffusion distance
Capillaries in every lamella and lamella are very thin
Why must fish that swim faster have a larger surface area of gills
They need to respire faster for a faster rate of muscle contraction in the fish. So they need to uptake more oxygen by diffusion to do respiration at a faster rate. A larger surface area of gills helps diffuse more oxygen into the fish