医学精品课件：13.专业英语（CELL TISSUE ORGAN）

Cells,Tissues,andOrgansHaijianXIA（夏海坚）,AssociateProfessor,Ph.D.,M.D.DepartmentofNeurosurgeryTheFirstAffiliatedHospitalofChongqingMedicalUniversityxiahaijian1@TheCellThebodycanbestudiedfromitssimplesttoitsmostcomplexlevel,beginningwiththecell,thebasicunitoflivingorganisms.Cellscarryoutmetabolism,thesumofallofthephysicalandchemicalactivitiesthatoccurinthebody.ProvidingtheenergyformetabolicreactionsisthechemicalATP(adenosinetriphosphate),commonlydescribedastheenergycompoundofthecell.Themaincategoriesoforganiccompoundsofthecellare:•Proteins,whichincludetheenzymes,somehormones,andstructuralmaterials.•Carbohydrates,whichincludesugarsandstarches.Themaincarbohydrateisthesugarglucose,whichcirculatesinthebloodtoprovideenergyforthecells.

•Lipids,whichincludefats.Somehormonesarederivedfromlipids,andadipose(fat)tissueisdesignedtostorelipids.Withinthecytoplasmthatfillsthecellaresubunitscalledorganelles,eachwithaspecificfunction.Themaincellstructuresarenamedanddescribedasbelow:Thenucleusisthecontrolregionofthecell.Itcontainsthechromosomes,whichcarrygeneticinformation.Eachhumancell,exceptforthesexcells,contains46chromosomes.Thechromosomesarecomposedofacomplexorganicsubstance,DNA(deoxyribonucleicacid),whichisorganizedintoseparateunitscalledgenes.Genescontroltheformationofenzymes,thecatalystsneededformetabolicreactions.Tohelpmanufactureenzymes,thecellsuseacompoundcalledRNA(ribonucleicacid),whichischemicallyrelatedtoDNA.Whenabodycelldivides,bytheprocessofmitosis,thechromosomesaredoubledandthenequallydistributedtothetwodaughtercells,whichisshownasbelow:Sexcells(eggandsperm)dividebyanotherprocess(meiosis)thathalvesthechromosomesinpreparationforfertilization.TissueCellsareorganizedintofourbasictypesoftissuesthatperformspecificfunctions:Epithelialtissuecoversandprotectsbodystructuresandlinesorgans,vessels,andcavities.Connectivetissuesupportsandbindsbodystructures.Itcontainsfibersandothernonlivingmaterialbetweenthecells.Includedareadipose(fat)tissue,cartilage,bone,andblood.Muscletissuecontractstoproducemovement.Therearethreetypesofmuscletissue:Skeletalorvoluntarymusclemovestheskeleton.Cardiacmuscleformstheheart.Itfunctionswithoutconsciouscontrolandisdescribedasinvoluntary.Smooth,orvisceralmuscleformsthewallsoftheabdominalorgans;itisalsoinvoluntary.Nervoustissuemakesupthebrain,spinalcord,andnerves.Itcoordinatesandcontrolsbodyresponsesbythetransmissionofelectricalimpulses.Thesimplesttissuesaremembranes.

Mucousmembranessecretemucus,athickfluidthatlubricatessurfacesandprotectsunderlyingtissue.

Serousmembranes,whichsecreteathin,wateryfluid,linebodycavitiesandcoverorgans.ecdbabadecOrgansandOrganSystemsTissuesarearrangedintoorgans,whichservespecificfunctions.Theorgans,inturn,aregroupedintosystems.Bearinmind,however,thatthebodyfunctionsasawhole—nosystemisindependen