Gas Exchange in Fish, Insects and Single Celled Organisms
- Created by: That Vet Student
- Created on: 14-11-20 11:38
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- Gas Exchange
- Fish
- The problem for fish is the oxygen concentration is lower in water
- Water enters through the mouth and is forced over the gills.
- Leavers via the gill cover
- Large Surface Area
- Lamellae increases surface area even more, this is where gas exchange occurs
- Many gill filaments
- Short Diffusion Pathway
- Lamellae only one/two cells thick
- Short diffusion path between blood and water
- Counter-Current Flow
- Blood and water flow in different directions across lamellae
- Steep Concentration Gradient across along whole length of gill
- Continuously occurring across whole length of gill
- Gas Exchange surface is the gills
- Single Celled Organisms
- No gas exchange system
- Short Diffusion Pathway
- Cells close as possible to external environment
- Gas Exchange Surface is the cell surface membrane
- Insects
- The problem for insects is that they lose water from their GE surface
- Many tracheae and many small branching tracheoles ensure a Large Surface Area
- Ventillation
- Air enters through the spiracles and into the tracheae
- Terrestrial insects limit water loss by closing spiracles
- Body movements help to move air in and out
- Air sacs ensure air is always present, making gas exchange more efficient
- A Steep Concentration Gradient is maintained by aerobic respiration in cells, uses up O2 and produces CO2
- Gas Exchange Surface is the spiracles
- Fish
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