Biol 200B 1st Edition Lecture 13Current LectureChapter 44 Animal Nutrition I. MacronutrientsII. Food processingIII. Symbiosis in digestionIV. Feedinga. mouthparts b. digestive tractChapter 45 Gas ExchangeI. Gas ExchangeII. Partial PressureIII. Fick’s Law of DiffusionIV. Connective transportV. Blood and transport of gasesGas ExchangeO2 - required for aerobic respiration (cellular production of ATP)CO2 - waste product of aerobic respirationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Gas exchange is driven by diffusionMost animals require respiratory exchange and circulatory distribution systemPartial Pressure (PO2)… Px = Fx(Ptotal)P(O2) = (% O2) x (total pressure)O2 and CO2 diffuse down their partial pressure gradientOxygen centration varies by environmental medium -air holds more O2 than water-colder water holds more O2 than warmer-solute concentration (freshwater > seawater)-atmospheric pressure-depth (shallow > deep)-surface areaFick’s Law of Diffusionrate of diffusion = k x A x (P2 - P1)/Dk = diffusion constantA = area for gas exchangeP2-P1 = difference in partial pressureD = distanceGood gas exchange: -high surface area-maintain steady partial pressure gradient-be thin Terrestrial Insects: trachea - ventilation, diffusion; spiraclesCutaneous (skin) gas exchange in vertebratesConnective gas exchange strategies•countercurrent (blood in gills, gill filament and gill lamella, flow in opposite direction of water) •cross-current•tidal exchange (humans)Ventilation with lungs -negative pressure: sucking in air-positive pressure: swallowing airBlood and Transport of gases-hemoglobin: O2 transport-cooperative binding of O2 to hemoglobin -oxygen-hemoglobin equilibrium curveHemoglobin Affinity for O2 can change: Bohr
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