Lecture 20 - BIOL104-04 Principles of Biology I Lecture#20...

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BIOL104-04 Principles of Biology I October 13, 2010 Lecture #20 Ch 49 Respiratory System
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Introduction to Respiratory System • Every cell in the body must exchange material with its surrounding environment – Single cells organism exchange occurs directly across membrane – Multicellular organisms require specialized • Structural adaptations to increase surface area allows the needs of every cell to be met
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Introduction to Gas Exchange • Cellular respiration in mitochondria – Uses O 2 and produces CO 2 as waste • Challenge for multicellular organisms – Obtaining sufficient oxygen – Disposal of excess carbon dioxide • Respiration at body system level involves – Mechanics of breathing 2 in respiratory organs
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Gas Exchange Involves Ventilation, Circulation & Respiration
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Gas Exchange Involves Diffusion Across Membranes • External environment in gas exchange is always aqueous • Terrestrial vertebrates – Oxygen from air dissolves in a thin layer of liquid that covers the respiratory surfaces • Diffusion process is passive – Driven by the O 2 2 concentrations on two sides of the membrane – For dissolved gases concentration is expressed as pressure
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Fick’s Law of Diffusion • Five things govern the rate of diffusion – Solubility of the gas in the aqueous film lining the gas exchange surface – Temperature – Surface area available for diffusion – Difference in partial pressures of the gas across the gas-exchange surface – Thickness of the barrier to diffusion
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Fick’s Law of Diffusion
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Evolutionary strategies have maximized gas diffusion
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This note was uploaded on 05/03/2011 for the course BIOL 104 taught by Professor Bray-speth during the Fall '11 term at Saint Louis.

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Lecture 20 - BIOL104-04 Principles of Biology I Lecture#20...

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