托福阅读理解冲刺题_1.docx

托福阅读理解冲刺题托福阅读理解冲刺题2017托福阅读理解是很多考生的心中之痛，现在yjbys考试网小编为了帮助考生顺利通过托福考试，专门推出以下托福阅读理解冲刺题一文。HormonesintheBodyUptothebeginningofthetwentiethcentury,thenervoussystemwasthoughttocontrolallcommunicationwithinthebodyandtheresultingintegrationofbehavior.Scientistshaddeterminedthatnervesran,essentially,onelectricalimpulses.Theseimpulseswerethoughttobetheengineforthought,emotion,movement,andinternalprocessessuchasdigestion.However,experimentsbyWilliamBaylissandErnestStarlingonthechemicalsecretin,whichisproducedinthesmallintestinewhenfoodentersthestomach,eventuallychallengedthatview.Fromthesmallintestine,secretintravelsthroughthebloodstreamtothepancreas.There,itstimulatesthereleaseofdigestivechemicals.Inthisfashion,theintestinalcellsthatproducesecretinultimatelyregulatetheproductionofdifferentchemicalsinadifferentorgan,thepancreas.Suchacoordinationofprocesseshadbeenthoughttorequirecontrolbythenervoussystem;BaylissandStarlingshowedthatitcouldoccurthroughchemicalsalone.ThisdiscoveryspurredStarlingtocointhetermhormonetorefertosecretin,takingitfromtheGreekwordhormon,meaning“toexcite”or“tosetinmotion.”Ahormoneisachemicalproducedbyonetissuetomakethingshappenelsewhere.Asmorehormoneswerediscovered,theywerecategorized,primarilyaccordingtotheprocessbywhichtheyoperatedonthebody.Someglands(whichmakeuptheendocrinesystem)secretehormonesdirectlyintothebloodstream.Suchglandsincludethethyroidandthepituitary.Theexocrinesystemconsistsoforgansandglandsthatproducesubstancesthatareusedoutsidethebloodstream,primarilyfordigestion.Thepancreasisonesuchorgan,althoughitsecretessomechemicalsintothebloodandthusisalsopartoftheendocrinesystem.Muchhasbeenlearnedabouthormonessincetheirdiscovery.Someplaysuchkeyrolesinregulatingbodilyprocessesorbehaviorthattheirabsencewouldcauseimmediatedeath.Themostabundanthormoneshaveeffectsthatarelessobviouslyurgentbutcanbemorefar-reachinganddifficulttotrack:Theymodifymoodsandaffecthumanbehavior,evensomebehaviorwenormallythinkofasvoluntary.Hormonalsystemsare