biol_119_lecture_10B_9-23-09

biol_119_lecture_10B_9-23-09 - Lecture 10B, 9-23-2009...

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Lecture 10B, 9-23-2009 respiration
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Concept 42.5: Gas exchange occurs across specialized respiratory surfaces Gas exchange is the uptake of molecular oxygen (O 2 ) from the environment and the discharge of carbon dioxide (CO 2 ) to the environment. While often called respiration, this process is distinct from, but linked to, the production of ATP in cellular respiration.
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Exchange Gases diffuse down pressure gradients in the lungs and other organs Diffusion of a gas depends on differences in a quantity called partial pressure A gas always diffuses from a region of higher partial pressure to a region of lower partial pressure In the lungs and in the tissues O 2 and CO 2 diffuse from where their partial pressures are higher to where they are lower Since the atmosphere is 21% oxygen (by volume), the partial pressure of oxygen (abbreviated PO 2 ) is 0.21 x 760, or about 160 mm Hg. The partial pressure of CO
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biol_119_lecture_10B_9-23-09 - Lecture 10B, 9-23-2009...

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