29)GasExchange2Spr11Postred - Gas Exchange: Clever Tricks 1...

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1 Gas Exchange: Clever Tricks 1 ( Δ pp/ Δ x) ( Δ pp) Gas exchange - Diversity of Life Most important axes of diversity are: Phylogeny Size Metabolic Rate Medium Gas exchange organs Useful properties The Fick Equation Rate or Flow = -D*A* ( Δ pp/ Δ x). Want to maximize Rate Can’t do much about D - depends on the medium and the diffusing molecule A - Large area > large flow Δ pp - Difference in partial pressure > large flow Δ x - Thin boundary > large flow Some constraints - Fick equation applies to the materials you want to exchange by diffusion, and to materials you don’t want to exchange!
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2 Gas Exchange in Animals: Vertebrates General Principles: Ventilation vs. Circulation Two Pumps: ___________ - Movement of the respiratory medium Circulation - Movement of the blood Why have two pumps? Fig. 44.1 Water as a respiratory medium Relative to air, water is _______ in O 2 (1/30) _______ (50x) Slow for diffusion Dense (800x) Must move ___________ the mass of water to get an equivalent amount of oxygen! And, water can be quite variable in [O 2 ] Gas Exchange in Chordates Cephalochordates -The starting point for vertebrates Gas Exchange Across body surface Feeding Ciliary pump through “gill” slits Particles trapped on “gill” bars Transport Closed circulation No real _____ No pigments Vertebrates breathing in water Aren’t “fish” slow anyway? Do they need to be
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This note was uploaded on 02/01/2012 for the course BSCI 207 taught by Professor Higgins during the Spring '08 term at Maryland.

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29)GasExchange2Spr11Postred - Gas Exchange: Clever Tricks 1...

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