6. Gas Exchange post

6. Gas Exchange post - Gas Exchange Gas Exchange Cellular...

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Gas Exchange
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Gas Exchange Cellular Respiration vs. External Respiration Respiratory medium – Air (21% O 2 ) – Water (2% O 2 ) Respiratory surface Diffusion Area (directly proportional) Distance (inversely proportional) Moist
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Respiratory Medium – Water Advantages Respiratory surface always moist Disadvantage – Lower O 2 concentrations Warmer Salt Require a very efficient mechanism to obtain enough O 2
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Gills Outfoldings of the body surface Surface area often greater than surface area of body
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Gas Exchange Ventilation (increasing flow of respiratory medium) ensures O 2 -rich water is always present Natural currents Artificial currents Swimming Pumping Counter current exchange Capillaries run in opposite direction to current – Blood gain O 2 as it encounters water with larger % of O 2 – Gills can remove 80% of O 2 in water Reduces E cost of
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Respiratory Medium – Air Advantages – High concentration of O 2 Diffusion is much faster requiring less ventilation Ventilation requires less energy Disadvantages Evaporates moisture from respiratory surface Gills are unsuitable for air because the expansive wet membrane exposed to air would dehydrate
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This note was uploaded on 04/17/2008 for the course BIOL 112 taught by Professor Maze during the Spring '08 term at Lander.

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6. Gas Exchange post - Gas Exchange Gas Exchange Cellular...

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