《Food Nutriology》課件-1-神奇的人體3-內(nèi)分泌和神經(jīng)系統(tǒng)

TheRemarkableBody神奇的人體Thebody’scellsTheHormonalandNervousSystemsSummarizetheinteractionsbetweenthehormonalandnervoussystemsandnutrition:Inadditiontofluid,bloodcells,nutrients,oxygen,andwastes,thebloodalsocarrieschemicalmessengers,hormones,fromonesystemofcellstoanother.Hormonescommunicatechangingconditionsthatdemandresponsesfromthebody'sorgans.WhatDoHormonesHavetoDowithNutrition?Hormonesaresecretedandreleaseddirectlyintothebloodbyorgansknownasglands.

Glandsandhormonesaboundinthebody.Eachglandmonitorsaconditionandproducesoneormorehormonestoregulateit.Eachhormoneactsasamessengerthatstimulatesvariousorganstotakeappropriateactions.Forexample,whenthepancreas(agland)detectsahighconcentrationoftheblood'ssugar,glucose,itreleasesinsulin,ahormone.Insulinstimulatesmuscleandothercellstoremoveglucosefromthebloodandtostoreit.Theliveralsostoresglucose.Whenthebloodglucoselevelfalls,thepancreassecretesanotherhormone,glucagon,towhichtheliverrespondsbyreleasingintothebloodsomeoftheglucoseitstoredearlier.Thus,anormalbloodglucoselevelismaintained.Nutritionaffectsthehormonalsystem.Inpeoplewhobecomeverythin,forexample,analteredhormonalbalancecausestheirbonestolosemineralsandweaken.Overlythinwomenmayalsoceasetomenstruate,aprocessregulatedbyhormones.內(nèi)分泌和激素Insulinfunctions

Thehormonalsystemalsoaffectsnutrition.Hormones:Carrymessagestoregulatethedigestivesysteminresponsetomealsorfasting.Informthebrainaboutthedegreeofbodyfatness.Helptoregulatehungerandappetite.Influenceappetitechangesduringawoman'smenstrualcycleandinpregnancy.Regulatethebody'sreactiontostress,suppressinghungeranddigestion.Inaddition,analteredhormonalstatecontributestothelossofappetitethatsickpeopleoftenexperience.Whentherearequestionsaboutaperson'snutritionorhealth,thestateofthatperson'shormonesisoftenpartoftheanswer.

Glandssecretehormonesthatactasmessengerstohelpregulatebodyprocesses.KeypointsHowDoestheNervousSystemInteractwithNutrition?Thebody’sothermajorcommunicationsystemis,ofcourse,thenervoussystem.Withthebrainandspinalcordascentralcontrollers,thenervoussystemreceivesandintegratesinformationfromsensoryreceptorsalloverthebody-sight,hearing,touch,smell,taste,andothers-whichcommunicatetothebrainthestateofboththeouterandtheinnerworlds,includingtheavailabilityoffoodandtheneedtoeat.Thenervoussystemalsosendsinstructionstothemusclesandglands,tellingthemwhattodo.Thenervoussystem'sroleinhungerregulationiscoordinatedbythebrain.Thesensationsofhungerandappetiteareperceivedbythebrain'scortex,thethinking,outerlayer.Deepinsidethebrain,thehypothalamus

monitors

manybodyconditions,includingtheavailabilityofnutrientsandwater.

Tosignalhunger,thephysiologicalneedforfood,thedigestivetractsendsmessagestothehypothalamusbywayofhormonesandnerves.Thesignalsalsostimulatethestomachtointensifyitscontractionsandsecretions,causinghungerpangs(andgurglingsounds).Whenyourbrain'scortexperceivesthesehungersensations,youwanttoeat.Theconsciousmindofthecortex,however,canoverridesuchsignals,andapersoncanchoosetodelayeatingdespitehungerortoeatwhenhungerisabsent.Inamarvelousadaptationofthehumanbody,thehormonalandnervoussystemsworktogethertoenableapersontorespondtophysicaldanger.Knownasthefight-or-lightreaction,orthestressresponse,thisadaptationispresentwithonlyminorvariationsinallanimals,showinghowuniversallyimportantitistosurvival.Example：Whendangerisdetected,nervesreleaseneurotransmitters(神經(jīng)遞質),andglandssupplythecompoundsepinephrine（腎上腺素）andnorepinephrine（去甲腎上腺素）.Everyorganofthebodyresponds,andmetabolismspeedsup.Thepupils（瞳孔）oftheeyeswidensothatyoucanseebetter;themusclestenseupsothatyoucanjump,run,orstrugglewithmaximumstrength;breathingquickensanddeepenstoprovidemoreoxygen.Theheartracestorushtheoxygentothemuscles,andthebloodpressurerisessothatthefuelthemusclesneedforenergycanbedeliveredefficiently.Theliverpoursforthglucosefromitsstores,andthefatcellsreleasefat.Thedigestivesystemshutsdowntopermitallthebody'ssystemstoservethemusclesandnerves.Withallactionsystemsatpeakefficiency,thebodycanrespondwithamazingspeedandstrengthtowhateverthreatensit.Inancienttimes,stressusuallyinvolvedphysicaldanger,andtheresponsetoitwasviolentphysicalexertion.Inthemodernworld,stressisseldomphysical,butthebodyreactsthesameway.Whatstressesyoutodaymaybeacheckbookoutofcontrolorateacherwhosuddenlyannouncesapopquiz.Underthesestresses,youarenotsupposedtofightorrun,asyourancientancestorsdid.Yousmileatthe"enemy"andsuppressyourfear.Butyourheartraces,youfeelitpounding,andhormonesstillfloodyourbloodstreamwithglucoseandfat.Yournumber-oneenemytodayisnotasaber-toothedtigerprowlingoutsideyourcavebutadiseaseofmoderncivilization:heartdisease.Yearsoffatandotherconstituentsaccumulatinginthearteriesandstressesthatstraintheheartoftenleadtoheartattacks,especiallywhenabodyaccustomedtochronicunderexertionexperiencessuddenhighbloodpressure.Dailyexerciseaspartofahealthylifestylereleasespent-upstressandhelpstoprotecttheheart.Thenervoussystemandhormonalsystemregulatebodyprocesses,respondtotheneedforfood,governtheactofeating,regulatedigestion,andcallforthestressresponsewhenneeded.KeypointsThefluidsurroundingcells(extracellularfluid)isderivedfromthebloodinthecapillaries:itsqueezesoutthroughthecapillarywallsandflowsaroundtheoutsidesofcells,permittingexchangeofmaterials.Someoftheextracellularfluidreturnsdirectlytothebloodstreambyreenteringthecapillaries.Thefluidremainingoutsidethecapillariesformslymph,whichtravelsaroundthebodybywayoflymphvessels.Thelympheventuallyreturnstothebloodstreamneartheheartwherealargelymphvesselemptiesintoalargevein.Inthisway,allcellsareservedbythecardiovascularsystem.Thefluidinsidecells(intracellularfluid)providesamediuminwhichallcellreactionstakeplace.Itspressurealsohelpsthecellstoholdtheirshape.Theintracellularfluidisdrawnfromtheextracellularfluidthatbathesthecellsontheoutside.BloodCirculationAllthebloodcirculatestothelungs,whereitpicksupoxygenandreleasescarbondioxidewastesfromthecells.Thenthebloodreturnstotheheart,wherethepumpingheartbeatspushthisfreshlyoxygenatedbloodfromthelungsouttoallbodytissues.Asthebloodtravelsthroughtherestofthecardiovascularsystem,itdeliversmaterialscellsneedandpicksuptheirwastes.BloodCirculationofNewbornBabyAsitpassesthroughthedigestivesystem,theblooddeliversoxygentothecellsthereandpicksupmostnutrientsotherthanfatsandtheirrelativesfromtheintestinefordistributionelsewhere.Lymphaticvesselspickupmostfatsfromtheintestineandthentransportthemtotheblood.Allbloodleavingthedigestivesystemisrouteddirectlytotheliver,whichhasthespecialtaskofchemicallyalteringtheabsorbedmaterialstomakethembettersuitedforusebyothertissues.Later,inpassingthroughthekidneys,thebloodiscleansedofwastes.Notethatthebloodcarriesnutrientsfromtheintestinetotheliver,whichreleasesthemtotheheart,whichpumpsthemtothewaitingbodytissues.Water,Nutrients,andtheBloodToensureefficientcirculationoffluidtoallyourcells,youneedanamplefluidintake.Thismeansconsumingsufficientwatertoreplacethewaterlosteachday.Cardiovascularfitnessisessential,too,anditrequiresattentiontobothnutritionandphysicalactivity.Healthyredbloodcellsalsoplayarolefortheycarryoxygentoalltheothercells,enablingthemtousefuelsforenergy.Sinceredbloodcellsarise,live,anddiewit