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BIOL 4160 Exam 3Pulmonary capillariesExchanging gases with alveoliLoading O2, offloading CO2 – everything reverses Load O2, increase PO2, it binds to Hb Offloading CO2 – o1) Start to reverse direction of bicarb/CO2 reaction – convert bicarb to CO2o2) Carrier that performs chloride shift reverses direction; brings bicarb back in, exposes it to carbonic anhydrase, can make CO2 again o3) As you start to take in protons to make CO2, Hb releases the protons As you convert CO2 to bicarb, release proton; starts to decrease pH, which decreases the affinity of Hb for O2 – aids in O2 offloading – Hb lets go of O2Haldane Effect: At the same PCO2, oxygenated blood contains a lower total CO2 content, while deoxygenated blood contains a higher total CO2 content Presence of O2 decreases carrying capacity of blood for CO2 What is not affected? – Dissolved CO2 (O2 has no effect on dissolved CO2)Oxygenated blood – O2 starts to bind to Hb (high PO2)oWhen O2 binds to Hb, causes a conformational change in Hb – makes Hb a stronger acid higher tendency to release protons oBinding of O2 makes Hb a stronger acid so it lets go of protons – affects carrying capacity of CO2 oAffects how much is carried in the form of bicarb & how much is bound to Hb Decrease amount of bicarb – decrease carrying capacity for CO2Decrease amount of CO2 bound to Hb also decreases carrying capacityfor CO2oPresence of O2, increase how much O2 binds to Hb O2 binding to Hb causes it to be a stronger acid Hb has higher tendency to release protons (protons + bicarb make CO2 and water) –increasing protons drives reactiontoward making CO2, which decreasesthe amount of bicarb Hb has lower affinity for CO2 (decreaseamount of CO2 bound to Hb)Both result in decreased carryingcapacity for CO2Happens at respiratory membrane – CO2can diffuse away Acute mountain sickness can result from exposure to high altitude Higher you get, the lower the overall atmospheric pressureTherefore, decreased individual partial pressures as well (not as much driving force to get O2 into blood)At altitudes above 10,000 feet, dropped off plateau of O2-Hb dissociation curve
BIOL 4160 Exam 3oOnly decreases CO2 instead of also increasing amount of O2 oPut body in state of alkalosis – changed pH of body causes symptoms (fatigue,nausea) Acclimatization to high altitude (natives are small and barrel-chested from constant work ittakes to continue to get enough air) People who live there are acclimated Body detects lower than average O2, triggers erythropoietin, increases RBC production(each RBC carries less, but you have more of them)Synthesize BPG(BPG decreases affinity of Hb for O2) – so offload more O2 at tissuesIncrease production of nitric oxide– cause vasodilation – increase perfusion/delivery of blood – send more blood to entire body