獸醫(yī)專業(yè)英語（揚州大學(xué)）lesson th

LessonThirteenImmuneSystem精選pptNewwordsandphrasesAnatomicReceptorNomenclaturePrecursorThymusNaiveProgenyQuiescentHumoralMononuclearPhagocyteDendriticFollicularHematopoieticResidenceArchitectureCytokinesLangerhanscellGastrointestinalTonsilRecruitMicrobialVascularendothelialcells精選pptTheanatomicorganizationofthecellsandtissuesoftheimmunesystemisofcriticalimportanceforthegenerationofimmuneresponses.Thisorganizationpermitsthesmallnumberoflymphocytesspecificforanyoneantigentolocateandrespondeffectivelytothatantigenregardlessofwhereinthebodytheantigenisintroduced.Text精選pptTheadaptiveimmuneresponsedependsonantigen-specificlymphocytes,accessorycellsrequiredforlymphocyteactivation,andeffectorcellsthateliminateantigens.BandTlymphocytesexpresshighlydiverseandspecificantigenreceptorsandarethecellsresponsibleforthespecificityandmemoryofadaptiveimmuneresponses.

精選pptNaturalkiller(NK)cellsareadistinctclassoflymphocytesthatdonotexpresshighlydiverseantigenreceptorsandwhosefunctionsarelargelyininnateimmunity.Manysurfacemoleculesaredifferentiallyexpressedondifferentsubsetsoflymphocytes,aswellasonotherleukocytes,andthesearenamedaccordingtotheCDnomenclature.精選pptBothBandTlymphocytesarisefromacommonprecursorinthebonemarrow.Bcelldevelopmentproceedsinthebonemarrow,whereasTcellprecursorsmigratetoandmatureinthethymus.Aftermaturing,BandTcellsleavethebonemarrowandthymus,enterthecirculation,andpopulateperipherallymphoidorgans.精選pptNa?veBandTcellsarematurelymphocytes

thathavenotbeenstimulatedbyantigentobecomedifferentiatedlymphocytes.Whentheyencounterantigen,theydifferentiateintoeffectorlymphocytesthathavefunctionsinprotectiveimmuneresponses.EffectorBlymphocytesareantibody-secretingplasmacells.EffectorTcellsincludecytokine-secretingCD4+helperTcellsandCD8+cytolytic(orcytotoxic)Tlymphocytes(CTLs).精選pptSomeoftheprogenyofantigen-activatedBandTlymphocytesdifferentiateintomemorycellsthatsurviveforlongtimeperiodsinaquiescentstate.Thesememorycellsareresponsiblefortherapidandenhancedresponsestosubsequentexposurestoantigen.精選pptAccessorycellsfunctiontopromotetheactivationoflymphocytesandtoperformeffectorfunctionsthatmaybeenhancedbyhumoralorcell-mediatedadaptiveimmuneresponses.Accessorycellsincludemononuclearphagocytes,dendriticcells,andfolliculardendriticcells.精選pptTheorgansoftheimmunesystemmaybedividedintothegenerativeorgans(bonemarrowandthymus),wherelymphocytesmature,andtheperipheralorgans(lymphnodesandspleen),wherena?velymphocytesareactivatedbyantigens.BonemarrowcontainsthestemcellsforallhematopoieticandlymphoidcellsandisthesiteofmaturationofallofthesecelltypesexceptTcells.精選pptThelymphnodesarethesiteswhereBandTcellsrespondtoantigens

thatarecollectedbythelymphdrainingperipheraltissues.Lymphocytesinthespleenrespondtoblood-borneantigens.BothlymphnodesandspleenareorganizedintoBcellareas(follicles)andTcellareas(parafollicularzones).TheTcellareasarealsothesitesofresidenceofmaturedendriticcells,whichareaccessorycellsspecializedfortheactivationofna?veTcells.FolliculardendriticcellsresideintheBcellareasandservetoactivateBcellsduringhumoralimmuneresponsestoproteinantigens.Thedevelopmentofsecondarylymphoidtissuearchitecturedependsoncytokines.精選pptThecutaneousimmunesystemconsistsofspecializedcollectionsofaccessorycellsandlymphocytes

adaptedtorespondtoenvironmentalantigensencounteredintheskin.AnetworkofimmaturedendriticcellscalledLangerhanscellsispresentintheepidermisoftheskinthatservestotrapantigensandthentransportthemtodraininglymphnodes.精選pptThemucosalimmunesystemincludesspecializedcollectionsoflymphocytesandaccessorycellsorganizedtooptimizeencounterwithenvironmentalantigensintroducedthroughtherespiratoryandgastrointestinaland

genitourinarytracts.Peyer’spatchesintheintestinalwallandthetonsilsintheoropharynxareexamplesofmucosalimmunesystemtissue.精選pptLymphocyterecirculationistheprocessbywhichlymphocytescontinuouslymovebetweensitesthroughoutthebodythroughbloodandlymphatics,anditiscriticalfortheinitiationandeffectorphasesofimmuneresponses.Na?veTcellsnormallyrecirculateamongthevariousperipherallymphoidorgans,increasi