Acid and Base Balance and Imbalance酸碱平衡与不平衡ppt课件.ppt

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1、1AcidandBaseBalanceandImbalance2pHReviewpH=-log[H+]H+isreallyaprotonRangeisfrom0-14If[H+]ishigh,thesolutionisacidic;pH<7If[H+]islow,thesolutionisbasicoralkaline;pH>73AcidsareH+donors.BasesareH+acceptors,orgiveupOH-insolution.Acidsandbasescanbe:Strong–dissociatecompletelyinsolutionHCl,NaO

2、HWeak–dissociateonlypartiallyinsolutionLacticacid,carbonicacid4TheBodyandpHHomeostasisofpHistightlycontrolledExtracellularfluid=7.4Blood=7.35–7.45<6.8or>8.0deathoccursAcidosis(acidemia)below7.35Alkalosis(alkalemia)above7.4556SmallchangesinpHcanproducemajordisturbancesMostenzymesfunctiono

3、nlywithnarrowpHrangesAcid-basebalancecanalsoaffectelectrolytes(Na+,K+,Cl-)Canalsoaffecthormones7ThebodyproducesmoreacidsthanbasesAcidstakeinwithfoodsAcidsproducedbymetabolismoflipidsandproteinsCellularmetabolismproducesCO2.CO2+H20↔H2CO3↔H++HCO3-8ControlofAcidsBuffersystemsTakeupH+orrelea

4、seH+asconditionschangeBufferpairs–weakacidandabaseExchangeastrongacidorbaseforaweakoneResultsinamuchsmallerpHchange9BicarbonatebufferSodiumBicarbonate(NaHCO3)andcarbonicacid(H2CO3)Maintaina20:1ratio:HCO3-:H2CO3HCl+NaHCO3↔H2CO3+NaClNaOH+H2CO3↔NaHCO3+H2O10PhosphatebufferMajorintracellularb

5、ufferH++HPO42-↔H2PO4-OH-+H2PO4-↔H2O+H2PO42-11ProteinBuffersIncludeshemoglobin,workinbloodandISFCarboxylgroupgivesupH+AminoGroupacceptsH+SidechainsthatcanbufferH+arepresenton27aminoacids.122.RespiratorymechanismsExhalationofcarbondioxidePowerful,butonlyworkswithvolatileacidsDoesn’taffectf

6、ixedacidslikelacticacidCO2+H20↔H2CO3↔H++HCO3-BodypHcanbeadjustedbychangingrateanddepthofbreathing133.KidneyexcretionCaneliminatelargeamountsofacidCanalsoexcretebaseCanconserveandproducebicarbionsMosteffectiveregulatorofpHIfkidneysfail,pHbalancefails14RatesofcorrectionBuffersfunctionalmos

7、tinstantaneouslyRespiratorymechanismstakeseveralminutestohoursRenalmechanismsmaytakeseveralhourstodays151617Acid-BaseImbalancespH<7.35acidosispH>7.45alkalosisThebodyresponsetoacid-baseimbalanceiscalledcompensationMaybecompleteifbroughtbackwithinnormallimitsPartialcompensa