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1、智课网TOEFL备考资料托福阅读模拟试题及答案解析(三)摘要:托福阅读考试着重考察考生的速读理解能力信息定位能力等,想要更好的备考托福阅读一定要多做练习,以下是小编为大家整理的托福阅读模拟试题及答案解析(三),希望对大家有帮助!HormonesintheBodyUptothebeginningofthetwentiethcentury,thenervoussystemwasthoughttocontrolallcommunicationwithinthebodyandtheresultingintegrationofbehavior.Sc
2、ientistshaddeterminedthatnervesran,essentially,onelectricalimpulses.Theseimpulseswerethoughttobetheengineforthought,emotion,movement,andinternalprocessessuchasdigestion.However,experimentsbyWilliamBaylissandErnestStarlingonthechemicalsecretin,whichisproducedinthesmallinte
3、stinewhenfoodentersthestomach,eventuallychallengedthatview.Fromthesmallintestine,secretintravelsthroughthebloodstreamtothepancreas.There,itstimulatesthereleaseofdigestivechemicals.Inthisfashion,theintestinalcellsthatproducesecretinultimatelyregulatetheproductionofdifferen
4、tchemicalsinadifferentorgan,thepancreas.Suchacoordinationofprocesseshadbeenthoughttorequirecontrolbythenervoussystem;BaylissandStarlingshowedthatitcouldoccurthroughchemicalsalone.ThisdiscoveryspurredStarlingtocointhetermhormonetorefertosecretin,takingitfromtheGreekwordhor
5、mon,meaning“toexcite”or“tosetinmotion.”Ahormoneisachemicalproducedbyonetissuetomakethingshappenelsewhere.Asmorehormoneswerediscovered,theywerecategorized,primarilyaccordingtotheprocessbywhichtheyoperatedonthebody.Someglands(whichmakeuptheendocrinesystem)secretehormonesdir
6、ectlyintothebloodstream.Suchglandsincludethethyroidandthepituitary.Theexocrinesystemconsistsoforgansandglandsthatproducesubstancesthatareusedoutsidethebloodstream,primarilyfordigestion.Thepancreasisonesuchorgan,althoughitsecretessomechemicalsintothebloodandthusisalsoparto
7、ftheendocrinesystem.Muchhasbeenlearnedabouthormonessincetheirdiscovery.Someplaysuchkeyrolesinregulatingbodilyprocessesorbehaviorthattheirabsencewouldcauseimmediatedeath.Themostabundanthormoneshaveeffectsthatarelessobviouslyurgentbutcanbemorefar-reachinganddifficulttotrack
8、:Theymodifymoodsandaffecthumanbehavior,evensomebehaviorwenormallythinkofasvoluntary.Hormonalsyst