8 Respiration 1 Gas Exchange

8 Respiration 1 Gas Exchange - • P O 2 at sea level is...

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Respiration I. Gas exchange A. Cellular versus organismal B. Requirements for organismal gas exchange C. Diffusion of gases in air versus water II. Respiration in animals via specialized organs: A. Gills B. Lungs - structure and ventilation III. Gas transport in blood
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Respiration - cellular versus organismal
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Requirements of a Respiratory System: 1. Adequate surface area for gas exchange (diffusion) 2. Means of keeping moist 3. Means of transporting O 2 to the body (circulation) 4. Means of assuring enough O 2 is present (ventilation) 5. Protecting delicate tissues Diffusion of Gases: Diffusion of a gas depends on it’s partial pressure (P O 2 for oxygen) • % of total pressure contributed by that gas atmospheric pressure at sea level is 760 mm Hg air is 21% oxygen
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Unformatted text preview: • P O 2 at sea level is therefore 0.21 X 760 = 160 mm Hg Amount of a gas that dissolves in liquid is proportional to: • partial pressure of that gas in air • solubility of the gas in water Properties of Air versus Water: Water Air Ratio (water:air) O 2 concentration (liter/liter) 0.007 0.209 1:30 Density (kg/liter) 1 0.0013 800:1 • Rate of diffusion of gases much higher (10,000 X) in air than in water. • Gas exchange across respiratory surfaces only possible in moist habitat. Respiration in: Advantages Disadvantages Air • high O 2 availability • dehydration • fast diffusion of O 2 • low density Water • always moist • low O 2 availability • slow diffusion of O 2 • high density...
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This note was uploaded on 10/21/2011 for the course BIO 102 taught by Professor Robinson during the Spring '09 term at UPenn.

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8 Respiration 1 Gas Exchange - • P O 2 at sea level is...

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