BIOA02H3 Chapter : BGYA02 - Lec4 (text+lec combined notes)
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BIOA02H3 Full Course Notes
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Respiratory gases animals must exchange are o2 and co2. Diffusion is the only means by which respiratory gases are exchanged between the internal body fluids of an animal and the outside medium (air or water). No active transport mechanisms move respiratory gases across biological membranes: diffusion is driven by concentration differences, barometric pressure at sea level is 760 mmhg high. Because dry air is 20. 9 percent o2, the partial pressure of o2 at sea level is 20. 9 percent of 760 mmhg (159 mmhg): describing concentration of gases in liquid is different. Fick"s law applies to all systems of gas exchange: diffusion described by fick"s law of diffusion, q= da[(p1-p2) l] Q is the rate at which a gas such as o2 diffuses between two locations. D is the diffusion coefficient, which is a characteristic of the diffusing substance, the medium and the temperature. A is the cross-sectional area through which the gas is diffusing.
