water - 副本.ppt

water 演讲 徐丹单词 刘晓彬回答 童莉ppt 张敏敏 Water waterasapercentageofbodyweight水作为身体重量的百分比functionsofwaterspecialcharacteristicsofwater水的特殊特性 Waterisofvitalimportancetothebodyandconstitutesthegreatestportionofbodyweight Thehumanbodyconsistsof45 to75 water dependingonageandsex 水是至关重要的 是对身体体重最大的一部分 人的身体有45 至75 的水 根据年龄和性别有所不同 Waterasapercentageofbodyweight WaterCompartment Infant Adult Man Woman ElderlyPerson Extracellular Intravascular Interstitial Intracellular Totalbodywater 4 25 4 11 5 10 5 15 48 45 35 25 77 60 50 45 Water H2o isvitaltohumanlife Thebodycannotcarryonmostofitsactivitieswithoutit Waterperformsmanysignificantfunctionsinthehumanbody Itprovidesanefficientmediumfordeliveryofnutrientstothecellsandexportofwasteproductsfromthecells Itisespeciallyimportantinregulationofbloodpressureandfluidandelectrolytebalance 流体和电解质的平衡 Primarysolvent主要溶剂withinthebodyPrimarycompoundinallbodyfluids在所有体液中主要化合物SuspensionagentHelpsregulatebodytemperature bodypH andfluidpressuresinsideandoutsidecellsAssistsorparticipatesinchemicalreactionsMaybeendproductofchemicalreactions可能是化学反应的最终产物 TransportsnutrientsandoxygentocellsTransportswasteproductsawayfromcellsActsas bumper toprotectcellsandorgansLubricatestopreventouterwalls parietal fromrubbingagainstinnerwalls visceral oforgans Waterinsolutionwithothersubstances ParticipatesinmaintenanceofbloodpressureHelpsregulateacid baseandfluid electrolytebalanceFacilitatestheuseofwater solublevictamins CandB complex 便于使用的水溶性victamins WaterinSolutionwithOthersubstances Specialcharacteristicsofwater Agreatdifferenceintemperatureisneededtobringaboutaphysicalchangeinwater Waterdirectlyandindirectlyparticipatesinallchemicalreactionsthatoccurinthebody Waterisagoodsolvent Waterexertspressureagainstthewallsorvesselsthatcontainit Agraetdifferentintemperatureisneededtobringaboutaphysicalchangeinwater Waterboilsat100 212 andfreezesat0 32 Watercanbecomeasolid aliquid oragaswithonlyatemperaturechange Watertemperature however changerelativelyslowly Itneedsheattochangefromaliquidtoagas Theevaporationprocess changefromliquidtogas removesheatfromthebody Waterdirectlyandindirectlyparticipatesinallchemicalreactionsthatoccurinthebody Chemically eachwatermolecule H2O ismadeupoftwoelements hydrogenandoxygen Duringmetabolism numerouschemicalchangeinthebodyseparatewatermoleculesintotheircomponentelementsforuseelsewhere HydrogenisthemaincomponentofthepHsystemofthebody Oxidationistheprocessthroughwhichthebodyusesoxygentoformneedednewsubstances Indirectly wateractsasthesolutioninwhichotherchemicalsionize dissociate Whensubstanceschangeintoions theybecomeavailabletoparticipateinotherchemicalreactions Waterisagoodsolvent Asolventisaliquid thatdissolvessolutes Asoluteisthesubstancedissolvedinasolvent Manycompounds suchassaltsandsugars dissolveeasilyinwater Nutrientsandwastesaretransportedassolutesinwater Bodywatercontainstwomaintypesofsolutes nonelectrolytesandelectrolytes Nonelectrolytesincludeproteins glucose carbondioxide oxygen andorganicacids Electrolytesaresolutesthatgenerateanelectricalchargewhendissolvedinwater Waterfunctionsasasuspensionagent Manylargermolecules suchaslipidsandproteins areeasilysuspendedinwater Thesesuspensionsmustbekeptinmotion orthelargermoleculeswillsettletothebottom Anindividual sbloodpressurepartiallydependsonintravascularwaterasasuspensionagent withspecificamountsofproteins electrolytes andmineralsassolutes Waterexertspressureagainstthewallsorvesselsthatcontainit Thispressureisknownashydrostaticpressureandoccursbecausewaterhasweightandvolume Theamountofpressuredependsonthedepthoftheliquid Regardlessoftheamount waterinatall thincontainerexertsmorehydrostaticpressurethanwaterinashallowcontainer Osmoticpressureispressurethatdevelopswhenasemipermeablemembraneseparatestwosolutionscontainingdifferentconcentrationsofsolutes Inotherwords theamountofsolutesinwateraffectsthepressurethatthewatercanexertagainstsurroundingmembranes Thegreatertheamountofsolutes thegreatertheamountofpressure Thisprincipleisnormallymaintainedwithinverynarrowlimits Humanbodycellshaveanosmoticpressurenearlyequaltothatofthecirculatingfluidoftheblood Solutionsexertingequalpressuresonoppositesidesofthemembranearesaidtobeisotonic Strongersolutions comparedtothoseontheopposingsideofamambrane aresaidtobehypertonic Immersioninah