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Midterm

PHGY NOTES-MIDTERM 1.docx

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Department
Physiology
Course
PHGY 209
Professor
Ann Wechsler
Semester
Fall

Description
LectureBodyFluidsCellsSimpleststructuralunitsintowhichamulticellularorganismcanbedividedandstillretainfunctionscharacteristicoflife4typesofspecializedcells1Muscle2Neurons3Epithelial4ConnectivetissueOrganstwoormorekindsoftissuesarrangedinacertainorientationBodyfluidcompartmentsDividedinto2majorcompartments1ECF2ICFBodyWeight60H2O40ICF20ECF15ISF5PLASMA13ofbodywaterisECF23ofbodywaterisICFECFisdividedinto2majorand2minorsubcompartmentsi2majorISFandplasmaii2minorLymphandtranscellularfluidECFis7580ISF2025plasmaISFandplasmahasthesamecompositionexceptplasmahasagreaterproteinconcentrationEnvironmentsurroundingindividualcellsisvastlydifferentfromexternalenvironmentHomeostasisBodysinternalenvironmentistheECFFunctionoforgansistomaintainadynamicequilibriumhomeostasisNegativefeedbackchangeinthevariablebeingregulatedbringsresponsethatpushesthevariableintheoppositedirectionofthechangeHomeostaticcontrolsystemsminimizechangesininternalenvironmentbutcannotmaintaincompleteconstancyFeedforwardregulationanticipateschangeinacertainvariableandincreasesthespeedofthehomeostaticresponsesminimizingfluctuationsReflexarcreceptorafferentpathwayintegratingcentreefferentpathwayandeffectorProcessesrelatedtohomeostasisAcclimatizationimprovedabilitytorespondtoanenvironmentalstressinducedbyprolongedexposuretothestresswithoutanygeneticchangeBiologicalrhythmsprovideaFeedforwardcomponenttohomeostaticcontrolsystemsaRhythmsareinternallydrivenbybrainpacemakersbutaredirectedbyenvironmentalcuessuchaslightwhichservetophaseshiftresettherhythmswhenneededbIntheabsenceofcuesrhythmsfreerunBodywaterMediuminwhichiSolutesaredissolvediiMetabolicprocesstakesplaceWhataccountsforthelargevariationinwatercontentindifferentindividuals BONEandFAThavetheleastamountofwatercontentIfthewatercontentiscomputedasafractionofLEANBODYMASSthedifferencesbetweenindividualsbecomeinsignificantBodywaterdifferswithagegenderethnicityandweightAroundpubertywestarttonoticechangesinwatercontentbetweenMandFFgainmoresubcutaneousfatmorefatlesswaterMusclemasslostwithagelosewatercontentApproximationofbodywater50inF60inMso42LinMalesBODYWATERISREMARKABLYCONSTANTINHEALTHBODYWATERISINADYNAMICSTEADYSTATEInputIntakeoffluidsfoodoxidativewaterfrommetabolismOutputFecesurinelungsskinkidneysObligatorylossesAccountfor15LofwaterInsensible10LUrinestool05LFacultativelossesVarywithintakeUrinekidneyismajorhomeostaticorganINSENSIBLEPERSPIRATION1Purewater2Passiveevaporationaffectedbyambienttemperatureandrelativehumidity3Entireskinsurfaceeveninthosewithoutsweatglands4ContinuousSWEATING1Electrolytesolution2Activesecretion3Sweatglands4ActivatedbyheavyworkhightemperatureConstantbodywaterisessentialformaintainingnormalsoluteconcentrationsandbloodvolumepressureadequateO2supplyANegativeWaterBalance1Reducedintake2Excessivelossfromgut3Excesssweating4Highaltitudesexcesslossinexpiredair5ExcessurinelossWaterIntoxication Bodyfluidsbecomeextremelydilutewaterentersburstcells1ExcessiveIntake2RenalFailureBODYWATERCOMPARTMENTSCompartmentsandsubcompartmentsmustNOTberegardedasrigidlyisolatedchambersCompartmentsallowforcontinuousinteractionswaterexchangesfreelybetweenthemPlasmaaccountsfor25ofECFso5ofbodyfluidSimilarlyInterstitialfluidaccountsfor75ofECFso15ofbodyfluidPLASMAMediuminwhichRBCsaresuspendedINTERSTITIALFLUIDISFfluidthatmovesbetweenindividualcellsinthebodymediatestheICFandplasmaandorgansISFtrueMilieuInteriorbecauseitisincontactwiththemajorbodyfluidsandactsasamediatorLYMPH12ofECFvolumefoundwithinthesystemofblindendedtubuleswhichpenetrateindividualcellsinmosttissuesDrainsinthevascularsystemandmixeswithbloodconstantcirculationwithlymphandbloodstream
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