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10/28/2015 My Biomedical Notebook: Respiratory Physiology http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 1/16 Notes in Biomedical Science My Biomedical Notebook Friday, 21 December 2012 Respiratory Physiology General Functions of the Respiratory System: Ventilation moving air into and out of the lungs Gaseous exchange replacing O2 and removing CO2 from the blood. Regulation of acidbase balance Air conditioning Speech/smell (Temperature and Fluid Balance) The structure of the respiratory system: two lungs: covered by visceral pleural and connect to the inner thorax and diaphragm branching network of airways respiratory membrane supporting tissues ''separated'' into: conducting and respiratory exchange zones 2013 (1) 2012 (18) December (18) Subjects and disciplines taught in Biomedica Scie... Centrifugation Optical Methods Chromatography Digestive System Nervous System Renal Physiology, Fluid and Electrolyte Bala Female Reproductive System and Pregnanc Endocrinology/Hormones Blood Respiratory Physiology Cardiovascular Function and dysfunction Post translational modification Translation (Protein synthesis) Posttranscriptional modification Transcription (RNA synthesis) DNA replication New user! Wot am I doing hier? Blog Archive Thanos Sofroniou Follow 17 View my complete profile About Me Endocrinology (1) Hematology (1) Molecular Biology (6) Neuroscience (1) Physiology (8) Practical Techniques and Skills (3) Categories 0 More Next Blog» [email protected] Dashboard

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  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 1/16

    NotesinBiomedicalScience

    MyBiomedicalNotebook

    Friday,21December2012

    RespiratoryPhysiology

    GeneralFunctionsoftheRespiratorySystem:VentilationmovingairintoandoutofthelungsGaseousexchangereplacingO2andremovingCO2fromtheblood.RegulationofacidbasebalanceAirconditioningSpeech/smell(TemperatureandFluidBalance)

    Thestructureoftherespiratorysystem:twolungs:coveredbyvisceralpleuralandconnecttotheinnerthoraxanddiaphragmbranchingnetworkofairwaysrespiratorymembranesupportingtissues''separated''into:conductingandrespiratoryexchangezones

    2013(1)

    2012(18)December(18)

    SubjectsanddisciplinestaughtinBiomedicalScie...

    Centrifugation

    OpticalMethods

    Chromatography

    DigestiveSystem

    NervousSystem

    RenalPhysiology,FluidandElectrolyteBalance

    FemaleReproductiveSystemandPregnancy

    Endocrinology/Hormones

    Blood

    RespiratoryPhysiology

    CardiovascularFunctionanddysfunction

    Posttranslationalmodification

    Translation(Proteinsynthesis)

    Posttranscriptionalmodification

    Transcription(RNAsynthesis)

    DNAreplication

    Newuser!WotamIdoinghier?

    BlogArchive

    ThanosSofroniouFollow 17

    Viewmycompleteprofile

    AboutMe

    Endocrinology(1)Hematology(1)MolecularBiology(6)Neuroscience(1)Physiology(8)PracticalTechniquesandSkills(3)

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  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 2/16

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 3/16

    Conductingzone:tracheasegmentalbronchibronchiolesterminalbronchioles

    Humidify,warmandfiltertheairtoPROTECT

    Respiratoryexchangezone:respiratorybronchiolesalveolarductsalveoliCreatelargesurfaceareaandthinbarriertoAIDDIFFUSION

    Knowthefunctionsofthelungsandrespiratorysystemandtheanatomicalandfunctionalzonesoftherespiratorysystem

    NOW!LetstalkaboutthefollowingThethoraxandrespiratorymusclesMechanicsofbreathingPressurechangesinventilation

    Zonesoftherespiratorysystem:

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 4/16

    MechanicsofBreathingvideo

    Whatcausesairtoflowinbulkintoandoutofthelungs?Expiration:DiaphragmmovesupInspiration:DiaphragmmovesdownAirPressureChangesDuringVentilationInspiration:P(atmosperic)>P(alveolar)=airmovesintothelungsExpiration:P(alveolar)>P(atmospheric)=airmovesoutofthelungs

    FactorsaffectinglungmechanicsLungcompliancethedistensibilityoflungtissueLungElasticitytheabilitytostretchandreturntorestingstateSurfactantproducedbytypeIIalveolarcellsreducessurfacetensioninalveoli(causedbyH2O)increasestotallungcomplianceAirwayresistanceaircontactwithwallsofairwaysincludingnarrowingofairwaysduetodisease/infectionetclikeAsthmaetc,Thiscausesmoreenergytoberequiredtodeliversufficientair

    Sotosummarizethemechanicsofbreathing:Inspiration:stimulustodiaphragm>diaphragmcontractsthoraxexpands>pressureinlungsdecreasesPatm>Palv>airflowsinbulkfromatmospheretoalveoli(fromhighpressuretolowpres.)Expiration:stimulustodiaphragmends>diaphragmrelaxesandthoraxmmovesinwards(passive)>pressureinlungsincreasesPalv>Patm>airflowsinbulkfromalveolitoatmosphere(fromhightolowpressure)

    NOW!letstalkabout:LungvolumesandventilationratesNervouscontrolofventilationChemicalcontrolofventilationCarbondioxide(PCO2)HydrogenIons(H+)Oxygen(PO2)

    Ventilationrates:AtrestPulmonaryventilationrate(minutevolume)=respiratoryrate(RR)xtidalvolume(Vt)=12Br/minx500ml=6000ml/minAlveolarventilationrate=(tidalvolumedeadspacevol.)xRR=(500150)x12=4200ml/min

    RegulationofVentilation:NeuralgenerationofrhythmicventilationVentilationdependsonrhythmiconoffstimmulationofrespiratorymusclesvianervesautomaticstimuluscomesfromtherespiratorycontrolcentreinMedullaofthebrainstem.

    attheendofexpiration=>restingmuscletoneneuronesrhythmically'fire'=>activeinspirationandthen'ceasefire'=>passiveexpiration

    Theneuralpathwaysforventilation

    WetSpirometry

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

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    DRGsendsanexcitatorystimulustothephrenicandintercostalnerveandthePons=>PhrenicandintercostalnerveconductthestimulustodiaphragmandintercostalmusclesActiveinspiration=>PneumotaxiccentreinPonssendsaninhibitorystimulusbacktotheDRGandinspirationstopsPassiveexpiration

    ControlofventilationbyPCO2PCO2ofarterialbloodisthemaininputregulatingventilationundernormalconditionsIncreasedPCO2stimulatesventilationviacentralandperipheralchemoreceptors

    CentralchemoreceptorsVentralsurfaceofMedullaissensitivetoCO2generated[H+]incerebrospinalfluid(CSF)surroundingmedulla.CO2+H2O>H2CO3>HCO3+H+pHofCSFismoresensitivethanbloodasitcontainsfewerproteinbuffersChangesinPCO2causeslarger[H+]inCSFcomparedtoblood.

    Peripheralchemoreceptorscarotidandaortic'bodies'largebloodsupplybothrespondtoPCO2generated[H+]andbloodpHCarotidalsostimulatedbydecreasedPO2PO2onlydetectedwhenitfallsby~40%(hypoxia/attitude)

    Othermodulatingfactorsincludeprotectivereflexesandhigherbraincentres

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 6/16

    Summary:lungvolumesandventilationrate,neuralcontrolofbreathingandchemicalcontrolviacentralandperipheralchemoreceptors

    Followingtopicsaboutrespiratoryphysiologytobediscussed:partialpressureofgasesO2andCO2transportinthebloodventilationandacidbasebalance

    PartialPressureofgasesDalton'slaw:thetotalpressureofagasmixtureisequaltothesumofthepressuresthateachgaswouldexertindependentlywhenbarometricpressure(Pb)is760mmHgThecompositionofatmosphericairis:O220.93%0.2093CO200.03%0.0003N279.04%0.7904

    Calculationofpartialpressures:thepartialpressureofanygascanbecalculatedbymultiplyingPbbythefractionofthegasExample:PO2=760x0.2093=...mmHgPN2=760x0.7904=...mmHg

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

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    ...mlofO2iscarriedby100mlofblood.0.3ml(...%)isdissolvedinsolutioninplasmaandtherestiscombinedwithiron(Fe2+)onhaemunitsofhaemoglobin(Hb)moleculesinredbloodcells.FourO2moleculescombinewithHbformingoxyhaemoglobininareversiblereaction.........arterialbloodisfullysaturatedwithO2.

    O2transportbytheblood

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 8/16

    Oxyhaemoglobindissociationcurve:Thisrelatesthepercent%........ofHbtothePO2inblood.AhighPO2=loading(curve>right)whereasalowPO2=reducedaffinity=unloading(curve

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

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    FactorsaffectinglungmechanicsTransmuralpressuregradientCompliance,elastance,airwayresistance,ST

    LungPressuresIntraalveolarpressure(IAP)=Pbatrest/+ve1mmHgmidwaythroughtidalbreathIntrapleuralpressure(IPP)4to8mHg

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

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    HelpskeepalveolipatentLosseswithage/disease

    AlveolarsurfacetensionforcesAtairliquidinterfaceSurfacetension(ST)a.drawsliquidsclosertogetherb.resistsincreaseinsurfacearea

    LawofLaplaceSTdirectsforce/pressuretocentreofbubbleConsequences:smallalveolimayhavegreaterP,maycreatepressuregradientsbetweenopposingalveolicausing'lunginstability'

    SurfactantPhospholipidproducedbytypeIIcuboidalalveolarcellsMoreconcentratedinsmallestalveoliSighingreplenishlevelsPreventssmallalveoliemptyingintolargeronesPreventscollapseofalveoliKeepslungsdryish(osmotic>hydrostaticpressure)ReducessurfacetensionandincreasestotallungcomplianceIncreaseslung'stability'Reducesworkofbreathing

    Surfactant:PathophysiologyAdequatelevels6weeksbeforebirthNRDSrequires+vepressurebreathingandsyntheticsurfactantLevelsreducedbyalveolardamageandincreasedmacrophageactivityEnergyisneededtoovercome'elasticresistance'oflungsandthorax.Posture:lying=decreaseincomplianceDisease:ifFRCisincreased,Clisincreasedandviceversa

    Solungcomplianceisaffectedby?FibrosisdecreaseOedemadecreaseAgedecreaseAirwayblockagedecreaseEmphysemaincrease

    AirwayResistanceGasflowproportionaltopressuregradientandinverselyproportionaltoresistancePoiseuillesLawResistanceproportionaltolength(L)andviscocity()andinverselyproportionaltoRadius(R)

    RproportionaltoLx/r^4Ifradius=1:1/1^4=>R=1Ifradius=2:1/2^4=>R=Thereforedoubletheradious=1/16ththeresistanceandviceversaRadiusisprimarysourceTracheaandbronchi(rigidandsmallXSarea)=90%Bronchioles=10%(largeXSarea)Narrowingofsmallerairwaysproblemsdependsonnumberaffectedandcollapse

    BrionchiolesReflexcontrolbyPSNSandhormonesLocalcontrolbyparacrines

    LawofLaplace

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

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    Topicstobediscussednowingreaterdetail:Gaspressuresandgasexchange(recapabove)TypesofventilationVentilationandperfusionFactorsaffectinggasexchange

    Remembercompositionofatmosphericair

    O220.90%,0.2090(fraction),159mmHg(partialpressure)CO20.04%,0.0004,0.3mmHgN278.60%,0.7860,597mmHgH200.46%,0.0046,3.7mmHgtotal100%,1.0,760mmHginrealitytherearesomeothercomponentsintheairaswellbutinverylowconcentrationsthatwecanactuallyneglect

    PartialPressure:thepartialpressureofanygascanbecalculatedbymultiplyingPbbythefractionofthegasExample:PO2=760x0.2090=159mmHgPN2=760x0.7860=597mmHg

    (missing5thslideofpulm3BS2049module)

    CompositionofalveolargasAffectedby:Ambientaircompositionandflow,gasexchange,mixingofgases,humidity

    TypesventilationUpneaHyperneaHyperventilationHypoventilationTachypneaDyspneaApnea

    10,12slidenotincludedputitin...

    V/QmatchingLocalmechanismsadjustforpoorairflowand/orpoorbloodflowCapillariescollapsibleRegulationofarteriolesandbronchioles

    Va/QaratioAlveolarbloodflowdecreasesfrombasetotheapexRatio=3.0inapexand0.5inbaseAverage=0.8(Va=5LQa=6L)Perfusion>Ventilationatrest

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 12/16

    Abovewediscuss:partialpressures,effectsofbreathingpattern,definingtypesofventilation,effectsofhyper/hypoventilationonPAO2/PACO2,V:Qmatching,localcontrolofairandbloodflow

    TopicsFick'slawofdiffusionOxygenationofbloodinpulmonarycapillariesGasexchange:problems

    TypesofHypoxia:Hypoxic:lowarterialO2Anaemic:lowHbO2Ischemic:lowPO2deliveryHistotoxic:lowO2use

    Fick'slawofdiffusion:Diffusionisproportionalto:partialpressuredifference(gradient)surfaceareaDiffusionisinverselyproportionalto:membranethicknessdiffusiondistance

    Gasexchange:ProblemsCausehypoxiaandhypercapnia:Inadequate:O2inalveoliTransferofO2fromalveolitobloodTransport....Gasexchange:InadequateO2

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 13/16

    abnormalairinadequatealveolarVe

    Gasexchanges:inadequaciesintranferdecreaseinSAforexchangeincreaseinthicknessofmembraneincreaseindiffusiondistance

    Someessayquestionthatareseeninexams:TheimpactofemphysemaonrespiratoryfunctionGasexchange:lossofalveolartissuedecreasedSAforgasexchange,lossoftraction>obstructionofairways,gastrapping>diffusiongradientaffectedLocalregulationofventilationandperfusion(V/Q)inthelungsMechanicsthatregulateventilationandperfusion(V/Q)inthelungFactorsthataffecttheefficiencyofgasexchangeinthelungsFactorsthataffectlungmechanicsandgasexchangeinhealthanddiseaseFactorsthataffecttheefficiencyofgasexchangebetweenthelungsandblood

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

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    nowwehavedonethisabovebutwewillextendabitfurtheronsomethingsparticularlyonexercise(justabit)Neuralandchemicalcontrolofventilationthemainareasofthebrainresponsiblefornormalcontrolofnormalventilationchemoreceptionandotherinfluencesresponsesduringexercise

    Respiratorycontrolduringexercise:TheOxygenuptakeresponseVentilatorycontrol:mechanismsrelationshipswithenergydemand

    Onthecurveontheleft,at50secthereisoxygendeficitat150secVO2atsteadystate

    Respiratorycontrol

    CONTROLCENTRES

  • 10/28/2015 MyBiomedicalNotebook:RespiratoryPhysiology

    http://tsbiomed.blogspot.in/2012/12/notesinrespiratoryphysiology.html 15/16

    AerobicmetabolismSupplies100%ofenergyrequirementstomatchlowtomoderatedemandsProcessesareratelimitedRelativelyslowtoadaptSupportedbyanaerobicprocessestomeetdemandatthestartSupportedbyanaerobicprocessestomeetdemandformoderatetoheavydemand.

    VentribularcontrolduringexerciseAssociatedwithcombinationand/orsimultaneouseffectof:a.chemicalfactorsb.neurologicalfactors

    Wecanseethreedifferentstatesatrightcurveforaconstantworkload

    NonChemicalcontrolVerisesinstantlywhenexercisestartsfollowedbyashort(

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    1comment:

    ValentinaGavaChakr 21April2014at16:58

    Congratulations for youblog! I'd like to know the sourceof figures (a,b,c,d,e) from "gasexchange".Thanks,ValentinaChakr,paediatricpulmonologistinBrazil.

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