Fish Gas Exchange Flashcards
(14 cards)
Do fish have a large or small SA:V ration?
Small- why they require a gas exchange surface (gills)
Does water contain more or less oxygen than air?
Less- fish have an adaptation to maintain the cod gradient to enable diffusion to occur
Key features in the gas exchange surface?
Large SA:V ratio
Short diffusion distance
Conc gradient maintained
What is ficks law?
Diffusion is directly proportional to surface area x difference in concentration divided by diffusion distance
How many layers of gills are there on both sides of the head?
4 layers of gills
What are the gills made up of?
Stacks of gill filaments
What is each gill filament covered in?
Gill lamellae which are positioned at right angles to the filament— which creates a large surface area
What happens when fish open their mouth?
Water rushes in and over the gills and then out through a hole in the sides of their head
How is large SA:V ratio established?
Created by many gill filaments covered in many gill lamellae
Short diffusion distance?
Capillary network in every lamellae
Very thin gill lamellae
Maintaining conc gradient?
Countercurrent flow mechanism
What is countercurrent flow?
Water flows over the gills in the opposite direction to the flow of blood in the capillaries
Countercurrent flow ensures that equilibrium is not reached
Ensures that a diffusion gradient is maintenance across the entire length of the gill lamellae
What do gill rakers do?
they trap solid matter
Describe the process for how a continuous flow of water is maintained across the gills?
1) fish opens mouth- the bucall and opercular cavities expand so there is an increased volume and a decreased pressure. Water fills the bucall cavity.
2) water flows into the opercular cavity down the pressure gradient and moves over the gills
3) opercular flap opens and cavity shrinks so water flows out
4) mouth opens and water starts to fill buccal cavity
