兽医专业英语lesson-thirteen课件

LessonThirteenImmuneSystemLessonThirteen1NewwordsandphrasesAnatomicReceptorNomenclaturePrecursorThymusNaiveProgenyQuiescentHumoralMononuclearPhagocyteDendriticFollicularHematopoieticResidenceArchitectureCytokinesLangerhanscellGastrointestinalTonsilRecruitMicrobialVascularendothelialcellsNewwordsandphrasesAnatomicF2Theanatomicorganizationofthecellsandtissuesoftheimmunesystemisofcriticalimportanceforthegenerationofimmuneresponses.Thisorganizationpermitsthesmallnumberoflymphocytesspecificforanyoneantigentolocateandrespondeffectivelytothatantigenregardlessofwhereinthebodytheantigenisintroduced.TextTheanatomicorganizationoft3Theadaptiveimmuneresponsedependsonantigen-specificlymphocytes,accessorycellsrequiredforlymphocyteactivation,andeffectorcellsthateliminateantigens.BandTlymphocytesexpresshighlydiverseandspecificantigenreceptorsandarethecellsresponsibleforthespecificityandmemoryofadaptiveimmuneresponses.

Theadaptiveimmuneresponsed4Naturalkiller(NK)cellsareadistinctclassoflymphocytesthatdonotexpresshighlydiverseantigenreceptorsandwhosefunctionsarelargelyininnateimmunity.Manysurfacemoleculesaredifferentiallyexpressedondifferentsubsetsoflymphocytes,aswellasonotherleukocytes,andthesearenamedaccordingtotheCDnomenclature.Naturalkiller(NK)cellsare5BothBandTlymphocytesarisefromacommonprecursorinthebonemarrow.Bcelldevelopmentproceedsinthebonemarrow,whereasTcellprecursorsmigratetoandmatureinthethymus.Aftermaturing,BandTcellsleavethebonemarrowandthymus,enterthecirculation,andpopulateperipherallymphoidorgans.BothBandTlymphocytesarise6NaïveBandTcellsarematurelymphocytes

thathavenotbeenstimulatedbyantigentobecomedifferentiatedlymphocytes.Whentheyencounterantigen,theydifferentiateintoeffectorlymphocytesthathavefunctionsinprotectiveimmuneresponses.EffectorBlymphocytesareantibody-secretingplasmacells.EffectorTcellsincludecytokine-secretingCD4+helperTcellsandCD8+cytolytic(orcytotoxic)Tlymphocytes(CTLs).NaïveBandTcellsaremature7Someoftheprogenyofantigen-activatedBandTlymphocytesdifferentiateintomemorycellsthatsurviveforlongtimeperiodsinaquiescentstate.Thesememorycellsareresponsiblefortherapidandenhancedresponsestosubsequentexposurestoantigen.Someoftheprogenyofantigen8Accessorycellsfunctiontopromotetheactivationoflymphocytesandtoperformeffectorfunctionsthatmaybeenhancedbyhumoralorcell-mediatedadaptiveimmuneresponses.Accessorycellsincludemononuclearphagocytes,dendriticcells,andfolliculardendriticcells.Accessorycellsfunctiontopr9Theorgansoftheimmunesystemmaybedividedintothegenerativeorgans(bonemarrowandthymus),wherelymphocytesmature,andtheperipheralorgans(lymphnodesandspleen),wherenaïvelymphocytesareactivatedbyantigens.BonemarrowcontainsthestemcellsforallhematopoieticandlymphoidcellsandisthesiteofmaturationofallofthesecelltypesexceptTcells.Theorgansoftheimmunesyste10ThelymphnodesarethesiteswhereBandTcellsrespondtoantigens

thatarecollectedbythelymphdrainingperipheraltissues.Lymphocytesinthespleenrespondtoblood-borneantigens.BothlymphnodesandspleenareorganizedintoBcellareas(follicles)andTcellareas(parafollicularzones).TheTcellareasarealsothesitesofresidenceofmaturedendriticcells,whichareaccessorycellsspecializedfortheactivationofnaïveTcells.FolliculardendriticcellsresideintheBcellareasandservetoactivateBcellsduringhumoralimmuneresponsestoproteinantigens.Thedevelopmentofsecondarylymphoidtissuearchitecturedependsoncytokines.Thelymphnodesarethesites11Thecutaneousimmunesystemconsistsofspecializedcollectionsofaccessorycellsandlymphocytes

adaptedtorespondtoenvironmentalantigensencounteredintheskin.AnetworkofimmaturedendriticcellscalledLangerhanscellsispresentintheepidermisoftheskinthatservestotrapantigensandthentransportthemtodraininglymphnodes.Thecutaneousimmunesystemco12Themucosalimmunesystemincludesspecializedcollectionsoflymphocytesandaccessorycellsorganizedtooptimizeencounterwithenvironmentalantigensintroducedthroughtherespiratoryandgastrointestinaland

genitourinarytracts.Peyer’spatchesintheintestinalwallandthetonsilsintheoropharynxareexamplesofmucosalimmunesystemtissue.Themucosalimmunesystemincl13Lymphocyterecirculationistheprocessbywhichlymphocytescontinuouslymovebetweensitesthroughoutthebodythroughbloodandlymphatics,anditiscriticalfortheinitiationandeffectorphasesofimmuneresponses.NaïveTcellsnormallyrecirculateamongthevariousperipherallymphoidorgans,increasingthelikelihoodofencounterwithantigendisplayedbyantigen-presentingcellssuchasmaturedendriticcells.MemoryandeffectorTcellsmoretypicallyarerecruitedtoperipheralsitesofinflammationwheremicrobialantigensarelocatedLymphocyterecirculationisth14LessonThirteenImmuneSystemLessonThirteen15NewwordsandphrasesAnatomicReceptorNomenclaturePrecursorThymusNaiveProgenyQuiescentHumoralMononuclearPhagocyteDendriticFollicularHematopoieticResidenceArchitectureCytokinesLangerhanscellGastrointestinalTonsilRecruitMicrobialVascularendothelialcellsNewwordsandphrasesAnatomicF16Theanatomicorganizationofthecellsandtissuesoftheimmunesystemisofcriticalimportanceforthegenerationofimmuneresponses.Thisorganizationpermitsthesmallnumberoflymphocytesspecificforanyoneantigentolocateandrespondeffectivelytothatantigenregardlessofwhereinthebodytheantigenisintroduced.TextTheanatomicorganizationoft17Theadaptiveimmuneresponsedependsonantigen-specificlymphocytes,accessorycellsrequiredforlymphocyteactivation,andeffectorcellsthateliminateantigens.BandTlymphocytesexpresshighlydiverseandspecificantigenreceptorsandarethecellsresponsibleforthespecificityandmemoryofadaptiveimmuneresponses.

Theadaptiveimmuneresponsed18Naturalkiller(NK)cellsareadistinctclassoflymphocytesthatdonotexpresshighlydiverseantigenreceptorsandwhosefunctionsarelargelyininnateimmunity.Manysurfacemoleculesaredifferentiallyexpressedondifferentsubsetsoflymphocytes,aswellasonotherleukocytes,andthesearenamedaccordingtotheCDnomenclature.Naturalkiller(NK)cellsare19BothBandTlymphocytesarisefromacommonprecursorinthebonemarrow.Bcelldevelopmentproceedsinthebonemarrow,whereasTcellprecursorsmigratetoandmatureinthethymus.Aftermaturing,BandTcellsleavethebonemarrowandthymus,enterthecirculation,andpopulateperipherallymphoidorgans.BothBandTlymphocytesarise20NaïveBandTcellsarematurelymphocytes

thathavenotbeenstimulatedbyantigentobecomedifferentiatedlymphocytes.Whentheyencounterantigen,theydifferentiateintoeffectorlymphocytesthathavefunctionsinprotectiveimmuneresponses.EffectorBlymphocytesareantibody-secretingplasmacells.EffectorTcellsincludecytokine-secretingCD4+helperTcellsandCD8+cytolytic(orcytotoxic)Tlymphocytes(CTLs).NaïveBandTcellsaremature21Someoftheprogenyofantigen-activatedBandTlymphocytesdifferentiateintomemorycellsthatsurviveforlongtimeperiodsinaquiescentstate.Thesememorycellsareresponsiblefortherapidandenhancedresponsestosubsequentexposurestoantigen.Someoftheprogenyofantigen22Accessorycellsfunctiontopromotetheactivationoflymphocytesandtoperformeffectorfunctionsthatmaybeenhancedbyhumoralorcell-mediatedadaptiveimmuneresponses.Accessorycellsincludemononuclearphagocytes,dendriticcells,andfolliculardendriticcells.Accessorycellsfunctiontopr23Theorgansoftheimmunesystemmaybedividedintothegenerativeorgans(bonemarrowandthymus),wherelymphocytesmature,andtheperipheralorgans(lymphnodesandspleen),wherenaïvelymphocytesareactivatedbyantigens.BonemarrowcontainsthestemcellsforallhematopoieticandlymphoidcellsandisthesiteofmaturationofallofthesecelltypesexceptTcells.Theorgansoftheimmunesyste24ThelymphnodesarethesiteswhereBandTcellsrespondtoantigens

thatarecollectedbythelymphdrainingperipheraltissues.Lymphocytesinthespleenrespondtoblood-borneantigens.BothlymphnodesandspleenareorganizedintoBcellareas(follicles)andTcellareas(parafollicularzones).TheTcellareasarealsothesitesofresidenceofmaturedendriticcells,whichareaccessorycellsspecializedfortheactivationofnaïveTcells.FolliculardendriticcellsresideintheBcellareasandservetoactivateBcellsduringhumoralimmuneresponsestoproteinantigens.Thedevelopmentofsecondarylymphoidtissuearchitecturedependsoncytokines.Thelymphnodesarethesites25Thecutaneousimmunesystemconsistsofspecializedcollectionsofaccessorycellsandlymphocytes

adaptedtorespondtoenvironmentalantigensencounteredintheskin.AnetworkofimmaturedendriticcellscalledLangerhanscellsispresentintheepidermisoftheskinthatservestotrap