Find v(t) for the circuit in Fig. 13.112.

WaterandFluidBalance Comprisesapproximately60%ofbodyweight Range_40-80% Functions -Aqueousmediumforchemicalreactions/cellprocess -Transportofsubstancesthroughthebody -Thermoregulation Fluidbalance -Watervolume -Soluteconcentration Euhydration=normalfluidbalance Osmosis -Movementofwaterthroughasemipermeablemembraneto areasofhighsoluteconcentration Tonicity -Hypotonic-watermovesin -Isotonic -Hypertonic-moresolubleoutside,watermovesout;cellsshrivel anddie Tonicity -Primarilyaffectedbyelectrolyteconcentration Waterconcentrationinbody -Averagemale-60%(approx.42Lfor70kg) -Averagefemale–50-55%(30L) Waterdistributioninbody -Bloodplasma -Muscles&otherorgantissues -Bone -Adiposetissue Distributionofbodywater Intracellularfluidcompartment -Approx.2/3ofbodywater Extracellularfluidcompartment -Approx.1/3ofbodywater(14Lor~3.5gallons) -Plasma -20%oftotalECFvolume(3Lor3Qrts) -Transport;thermoregulation Interstitialfluid–80%oftotalECF(11Lor3gallons) -Protection Lymphaticsystem Tonicity Hypertonicity -Heavysweating -Largelossofplasmavolume + -IncreasedconcentrationofplasmaNa -Watermovement Hypotonicity -Consumptionoflargeamountsofwaterveryquickly -Nervecellscanceasetofunctionproperly -Ex.3,000mlor~13Cin4hrs -DilutesECFresultingindecreasedplasmaNa + Watermovement Waterloss Insensible–H20lossthroughchannelsnotnormallynoticed Sensible Primarychannels–urine,sweat,feces Influencesonwaterloss -Fluid&saltintake -Renalfunction-majorroleinfluidbalancecontrol Actionofvarioushormones Consumptionofdiureticcompounds FluidBalance Diuretics -Alcohol–inhibitsproductionofADH -Prescriptionmedications-mayblockreabsorptionoffluid&/or electrolytes -Caffeine&theophylline–increasesurineoutput -Herbs Sweating-thermoregulatorymechanism Waterintake Averagedailyintake-~2,350mlfrombeverages&foods Food–20-25% Tapand/orbottledwater–35-40% Othersources–35-45% Aerobicmetabolism–350ml(12.5oz)ofdailywater Regulatedbywatervolume&osmolalityofECF Hypernatremia&enduranceathletes Clinicalhypernatremia–plasmalevel<135mmol/L Exercise-inducedhypernatremia–rapiddroplessthan130 Involvesenduranceeventslasting>7hrswithsignificant sweatloss Ultraendurancerunningevents–10% IronmanTriathletes–29% Swellingofnervecellscancausedizziness,confusion, seizure,coma,&death 0.5-0.7g/lfluid Strategiesforprevention ReplacementofNa&preventionoffluidoverload Eventslasting>2-3hrsshouldincludeNareplacement Sodiumintake Dailyintake ConsumedprimarilyasNaCl:1/4tspoftablesalt(1000mgofNaCl has40%Na)=1.5gNaCl Processedfood–77% Tablesalt–11% Naturallyinfoods–12% AveragedailyNaintake Males–4200mg Women–3300mg Exerciseandfluidbalance Undernormalconditions,fluidbalanceeasilyregulated Exercise:increasebodytempandfluidlossviasweating Decreaseinplasmavolume Leakageoffluidfromplasmaintotheinterstitialspaces Dependentonintensityofexercise Intenseexercise–smalllosses(5%)w/osweating Prolongedexercise–largelosses(10-20)w/sweating Exerciseandfluidbalance Factorsaffectingincreaseinsweating Exerciseintensity Environmentalconditions Clothing Trainingstatus-highersweatrates;moreeffective thermoregulatory Variationsinsweatloss Non-exercise,normaltemperatureenvironment-100ml Exercisinginelevatedtemperatures–300-1200ml/h Exercisinginelevatedtempswithprotectiveclothing–1-2l/h Athletescompetinginteamsports&prolongedenduranceevents inhotenvironments–2.5l/h Athletescompetinginaquaticevents Havebeenshowntohaveelevatedsweatrates Coldclimates–waterlossfromventilation Hypohydration Hypovolemia: Lossofbloodvolume:increaseosmolalityofplasma Increaseinbodycoretemperature:every1%lossofbody weightaswater,about0.1-23 cincreasecoretemp Impairmentinabilitytodissipateheatresultinginhigher bodytemperatures Decreasedthermoregulatorycontrolinbrain Mayresultinhyperthermialeadingtoheatstroke,coma& possiblydeath Electrolytelossduringexercise + - Greatestloss-Na andCl Exercising<2hrs:electrolytelossnotlikely;fluidreplacement shouldbefocusedonwaterintake Exercising>2hrs:electrolytereplacementwithsodium Replenishmentofwater&electrolytes Determininghydrationstatus Amountoftotalbodywater Plasmaosmolality Providesaccurateassessmentatsinglepointintime Analysisofurineoutput Higherspecificgravity,osmolality,&darkercolor seeninhypohydration Urinetestingstripsavailable Changesinbodyweight Weightlossfromsingleexercisesessionlikelyduetofluid loss Canbeusedasabenchmarkforsubsequentrehydration Ex.Athleteengagesinintenseexerciselastingone hour&loses2kg 1Lwaterweighs1kgwhichtranslatestolossof2Lof water Ifonly1kggainedbackthefollowingday,signifies inadequatefluidreplenishment Hydrationassessmenttool Pre-exercisehydration Pre-exercisebeverage Waternormallysufficientwithslowfluidintakebeginning atleast4hrsprior,ifpossible:5-7ml/kgshouldbesufficient Sodium–stimulatesthirstandretentionofbodyweight Carbohydrates -Recommendedadditionalintakeof3-5ml/kg-2hrspriors Hypohydrationstatepriortoexercise Inadequaterestorationoffluidfrompreviousday’sexercise Multipleexerciseboutsinhotand/orhumidconditions Voluntaryrestrictionoffluidtoreducebodyweight Amount&timingshouldbeindividualized Toolittlefluidintake:dehydration Toomuchfluidintakebloating Hydrationstrategyguidedby: Intensity&durationofactivity Potentialeffectofhypohydrationonperformance Environmentalconditions Intakeduringtraining&performance Goals Replacebodyfluid Delaydehydration Replacesodium AvoidoverconsumptionandGIdistress ACSMrecommendations Marathonrunners–0.4-0.8l/h Drinkorschedulew/goalnottolosemorethan 2%ofbodyweight CurrentGuidelines Developacustomizedplanthatconsiderssweatrate, sweatcomposition,duration,clothing,& environmentalconditions Replenishmentaftertraining&performance Goals: Replacewaterloss,sodiumandotherelectrolytes PlasmaNaincreasesduringexerciseduetolossofwater Consumptionofadequatecarbandprotein AvoidGIdistress Recommendations 1.5L/kgofbodyweightlost Nacontainingbeverages:exercisefor>4hrandheavy sweating Ivreplacement:noevidence