BIO 126 Lecture Notes - Lecture 5: External Intercostal Muscles, Cardiac Output, Countercurrent Exchange
21 Mar 2016
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Document Summary
Gas exchange moving co2 and o2 by diffusion. Air is comprised of 21% oxygen, 78% nitrogen, and <1% carbon dioxide and other gases. Atmospheric pressure: pressure exerted by the atmosphere on the body surfaces of animals, measure in mmhg or kpa, partial pressures of all the gases. Percentages remain the same, but the partial pressure can change with altitude. 760 mmhg is total pressure at sea level: atmospheric pressure decreases at higher elevations, diffusion is driven by partial pressure gradients, rate of oxygen diffusion into blood is lower at higher elevations. Solubility of gases: gases dissolve in solution (fresh water, sea water, or body fluids), but not always well, factors influencing solubility in water: Higher pressures = more gas in solution. Cold water holds more gas than warm water. Other solutes decrease the amount of gas that dissolves into solution. Ventilation is the process of bringing oxygenated water of air into contact with a gas exchange surface.
