淋巴系统与免疫.ppt
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淋巴系统与免疫.ppt
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Chapter22Anatomy&PhysiologyFifthEditionSeeley/Stephens/Tate(c)TheMcGraw-HillCompanies,Inc.TheLymphaticSystemandImmunityThehumanbodyrecognizesanythingotherthanitsownasaninvader.Whentheseforeignbodiesarecapableoflivinginthehumanbodyandareharmful,theyarecalledpathogens.Plasmacontainsantibodiesagainstcellsotherthanitsown.Theseantibodiesareformedwhentheinfantsareaboutthreemonthsold.Recallwhenthebloodtypeswereformed.Thus,thereisthelymphaticsysteminthebodytoidentifyanddestroyforeignbodies.(byformingantibodies)But,howdotheydistinguishourownfromtheothers?
Whenthereactionisagainsteachspecificforeignbody,itiscalledimmuneresponseorimmunity.OrganizationandFunctionsoftheLymphaticSystemInthelymphaticsystemthereare:
Lymphaticfluid,lymph,thatcontainslymphocytesVesselsthattransportlymphAndsiteswherelargecontentsoflymphocytesareheld:
lymphnodes,spleen,andthymus.a.FunctionsofthelymphaticsystemThelymphsystemhasthreemajorfunctions:
1.FluidBalance.Circulatingbloodreleaseabout30Loffluidintointerstitialspaceeachday.Ofthe27Larereturnedtothecirculation.Theremaining3Lwillenterthelymphaticsystemaslymph.Thelymphpassesthroughthelymphaticsystemandenterbacktothebloodvessels.Inadditiontowater,lymphcontainssubstancesasinplasmaandsubstancesextractedfromcells.2.FatAbsorption.Fatsandothersubstancesareabsorbedfromthedigestivetractandcarriedthroughthelymphaticsystem.3.Defense.Immunesystem(lymphocytes,B-cells,T-cells)b.LymphaticVesselsLymphaticvesselsarespreadoutthroughoutthebodyexceptintheCNS(Fig22.1)Theyoriginatefromwithinlymphocyteproducingorgansandemptyintothethoracicduct.Theycontainmanylymphaticnodesandnodules.Likebloodvessels,theyhavesmallvesselscalledlymphaticcapillarieswhichlayclosetothebloodcapillaries.Lymphsolublefluidwillbepickedupthroughthecapillariesandpushedbacktolargertruck.Theyevenhavevalvestocontroltheflowoflymphthroughverylowpressureoffluid.c.LymphaticOrgans1.Diffuselymphatictissue1.Dispersedlymphocytes,macrophagesandothercells.Noclearboundaries.(Fig.22.2)2.LymphoidNodules1.Packedwithlymphocytes.2.Flexibleinsizedependinguponthenumberoflymphocytes3.SpreadinlooseC.T.ofthedigestive,respiratoryandurinarysystems.LargerpatchesinintestinalsystemcallPeyerspatches.4.Inlymphnodestheyarecalledfollicles,theretheycontainagerminalcenter,wherelymphocytesdivide.5.Thoughfilledwithlymphocytes,lymphoidnodulescouldbeinfected:
tonsillitis,appendicitis.TonsilsLargegroupsoflymphnodulesanddiffuselymphatictissuelocatedintheoralcavity(Fig.22.3)Protectionagainstbacteria,etc.Inthenoseandmouth.Threetypesoftonsils:
pharyngeal,palatine,andlingualEnlargedpharyngealtonsiliscalledadenoid.LymphNodes(Fig.22.1andFig.22.4)Foundthroughoutthebodyexceptinthebrain.Theyareencapsulationoflymphocytes,macrophagesandreticularcellswithbloodvessels1-25mmindiameterandaresubdividedintotworegionscalled,amedullaandcortex.Withinthecortexgerminalcentersarefound.Thisiswherelymphocytedivisiontakesplace.Actassieveandremovalof99%ofantigenswhilereactivatingT-cellsandB-cells.TheSpleenUpperandposteriorpartoftheabdominalcavity.Largestofthelymphatictissue,160g.(Fig.22.5)Containstwotypesoflymphatictissue:
whitepulp(arterialsupply)andredpulp(venoussupply).Thespleendetectsandrespondstoforeignsubstancesintheblood,destroysworn-outRBCsandactsasabloodreservoir.ThymusGlandOntopoftheheartT-cellsmaturehereBecomeslargeduringthefirstorsecondyear.Intrinsicsizeislargestatpubertyandthendecreases.Produceslymphocyteswhichthenmovetootherlymphatictissues.Blood-thymicbarrier-reticularcellswraparoundcapillariesandpreventlargemoleculesfromenteringthecortexofthethymus.ImmunityHowthehumanbodydefendsitselfagainstdamagefromforeignsubstancessuchasmicroorganismsandharmfulchemicalastoxins.Innate(non-specific)andadaptive(specific)immunity.Thesetwotypesaredistinguishedbythewaytheyrespondtospecificstimulationsandhowtheymemorizetheevents.Specificity.Innateimmunitycanactagainstbacteriaingenera.(nomemory)Memory.Adaptiveimmunitycandistinguishamongdifferentkindsofbacteriaandgenerallygetmoresensitivewitheachnewencounter.InnateImmunitya.MechanicalMechanism1.Physicalbarriers,suchastheskinandmembranesb.ChemicalMediators(Table22.1)1.Moleculeswhichcontributetodevelopimmunity.2.Killbacteria:
lysozymeandsebummucus3.Others:
histamineandkininsbyvasodilation;interferonproduction,etc.4.Complement5.Isagroupofapproximately20proteinsthatmakesupapproximately10%oftheglobulinpartofserum.Theyareagroupofproteinsactivatedintheformofacascadeand
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