Substance Exchange- Non-mammalian Gas Exchange Systems Flashcards
What are the features of gas exchange systems?
- Large surface area
- Short diffusion distance
- Good blood supply/ventilation to maintain a diffusion gradient
Why are gas exchange systems necessary in multicellular organisms?
Multicellular organisms have a lower surface area to volume ratio, so need specialised exchange surfaces for efficient gas exchange of carbon dioxide and oxygen.
What is the structure of the fish gas exchange system?
Fish have four pairs of gills, with each gill supported by an arch. Along each arch there are projections called gill filaments, with projections on them called lamellea.
How does fish gas exchange work?
Blood and water flow across the lamellea in a counter current direction. This ensures a steep diffusion gradient is maintained.
Why can’t fish survive out of water?
The lamellea are held apart by water flow, and fish absorb oxygen from water.
How does ventilation occur in fish?
The fish opens its mouth, and the floor of the buccal cavity lowers, enabling water to flow in.
Then, the fish closes its mouth, raising the floor of the buccal cavity and raising the pressure.
The water is forced over the gill filaments by the difference in pressure between the mouth cavity and opercular cavity.
What is the function of the operculum?
It acts as a valve and a pump - lets water out and pumps it in.
What is the structure of the gas exchange system of terrestrial insects?
Insects have spiracles through which gases can pass into trachea and tracheoles.
How does the insect gas exchange system function?
Some gasses diffuse, and some get there through mass transport caused by muscle contraction and volume changes in the tracheoles.
Which adaptations in the leaves of plants allow gas exchange?
They have a large number of stomata, which enable gas exchange. The large number decreses the diffusion distance. There are also gaps in the leaves which allow gases to reach mesophyll cells
