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3 Cards in this Set
- Front
- Back
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Gas exchange in single celled organisms and insects (GENERAL) |
Large surface to volume ratio Oxygen absorbed through diffusion across body surface, which is covered by cell membrane Carbon Dioxide diffuses out |
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Gas exchange in insects |
Have internal set of tubes called tracheae Tracheae are supported by set of rings to stop it from collapsing Tracheae divide into smaller deadend tubes called tracheoles Atmospheric air is brought through the tracheoles to respiring body tissue so that there is a short diffusion pathway |
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Respiratory gas movement in tracheal system |
ALONG DIFFUSION GRADIENT - as oxygen is used up by respiring tissue, more oxygen will enter the tracheae and the tracheoles to travel to the area of a lower concentration. This is the same for carbon dioxide. MASS TRANSPORT - muscles in insects can squeeze the tracheae, which forces air in and out, which increases the speed of diffusion. THE ENDS OF TRACHEOLES ARE FILLED WITH WATER - during periods of intense activity, muscle cells around the tracheoles may start to respire anaerobically, which produces lactate. This lowers the water potential of the muscle cells. Water from the tracheoles is then forced into the muscle cells by osmosis. The reduced volume of water in the tracheoles increases the amount of air being drawn into them. This further reduces the diffusion pathway, which increases the rate of diffusion. |
