高中英语Unit9 Health care文章 What cancer is人教版第三册VIP免费

WhatcancerisCancerisadiseasecausedbynormalcellschangingsothattheygrowinanuncontrolledway.Theuncontrolledgrowthcausesalumpcalledatumourtoform.Ifnottreated,thetumourcancauseproblemsbyinvadingnormaltissuesnearbyorbycausingpressureonotherbodystructures.Thisisallexplainedmorefullybelow.Thereareover200differenttypesofcancerbecausethereareover200differenttypesofbodycells.Forexample,cellsthatmakeupthelungscancausealungcancer.Therearedifferentcellsinthelungs,sothesemaycausedifferenttypesoflungcancer.ThereismoreabouttypesofcellsandcancerinthissectionofCancerHelpUK.NormalcellsYourbodyismadeupofbillionsofcellsthatcanonlybeseenunderamicroscope.Thesecellsaregroupedtogethertomakeupthetissuesandorgansofourbodies.Theyareabitlikebuildingblocks.Differenttypesofbodytissuesaremadeupofdifferenttypesofbodycells.Therearebonecellsinboneandbreastcellsinthebreast,forexample.GenesandcancerTherearemanydifferenttypesofcellsinthebodywhichdodifferentjobs,buttheyarebasicallysimilar.Theyallhaveacentrecalledanucleus.Insidethenucleusarethegenes.Genesarereallybitsofcode.Theinformationtheycarrycanbeswitchedonoroff.Thegenescontrolthecell.Theydecidewhenitwillreproduce,whatitdoesandevenwhenitwilldie.用心爱心专心Normallythegenesmakesurethatcellsgrowandreproduceinanorderlyandcontrolledway.Ifthesystemgoeswrongforanyreason,theusualresultisthatthecelldies.Rarely,thesystemgoeswronginawaythatallowsacelltokeepondividinguntilalumpcalleda'tumour'isformed.ThereisinformationonthedifferencesbetweennormalcellsandcancercellsinthissectionofCancerHelpUK.Benignandmalignanttumoursumours(lumps)canbebenignormalignant.Benignmeansnotcancer.BenigntumoursUsuallygrowquiteslowlyDonotspreadtootherpartsofthebodyUsuallyhaveacoveringthatismadeupofnormalcellsBenigntumoursaremadeupofcellsthatarequitesimilartonormalcells.TheywillonlycauseaproblemiftheyGrowverylargeBecomeuncomfortableorunsightlyPressonotherbodyorgansAretakingupspaceinsidetheskullReleasehormonesthataffecthowthebodyfunctionsMalignanttumoursaremadeupofcancercells.TheyUsuallygrowfasterthanbenigntumoursSpreadthroughanddestroysurroundingtissuesSpreadtootherpartsofthebody用心爱心专心AnimatedVersionofDiagramItistheabilitytospreadthatmakesacancerdangerous.Ifacancerisnottreated,itcanthreatentheorgansneartowhereitstartedgrowing.Itcanalsodamageotherpartsofthebodybyspreading.PrimaryandsecondarycancerTheplacewhereacancerbeginsiscalledthe'primarycancer'.Butthecancercellscanspread.Theycanbreakawayandarecarriedinthebloodorlymphaticsystemtootherpartsofthebody.There用心爱心专心theycanstarttogrownewtumours.Cancerscanalsospreadtonearbybodytissues.Forexample,lungcancercanspreadtotheliningofthechest,thepleura.Ovariancancercanspreadtotheliningoftheabdomen(theperitoneum).Tumoursfromcancersthathavespreadarecalled'secondarycancers'.Doctorssometimescallthesemetastasesandsayacancerthathasspreadhas'metastasised'.Thevariousorgansofthebodyaremadeupofdifferenttypesofcells.Anyofthesecelltypescangrowintoaprimarycancer.Cancersfromdifferentcelltypesbehavedifferently.TheycanGrowatdifferentspeedsHavevariouseffectsonthebodybyreleasingchemicalsintothebloodBemoreorlesslikelytospreadinthebloodResponddifferentlytodrugsResponddifferentlytoradiationCancerscancausedifferentsymptomsindifferentpeoplebecauseofwheretheyare.Acancermaypressonanerve,oranotherbodyorganthatisnearby.Theplacewherethecancerstartsalsoaffectswhattreatmentcanbeusedbecausedoctorshavetotakeintoaccounttheriskofdamagingneighbouring用心爱心专心