05262015_body_defense

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1、•Whydoorganismscontractdiseases?•Whathappenswhenanorganismcontractsadisease?•Whatfactorscanhelp(orhinder)thelikelihoodthatwewillcontractadisease?•Whathappenswhenanorganismisinjured?•Whatfactorscanhelp(orhinder)thelikelihoodthatwewillrecoverfromaninjury?Unit4:TheBody’sD

2、efenses•Reading:Chapter24•LectureOutline:1.Innateimmunityandadaptiveimmunity2.TheLymphaticsandtheImmuneSystem3.HumoralandCell-MediatedImmuneResponses4.ImmuneDisordesTheFirstLineofDefense:Skin•Thedead,outerlayerofskin,knownastheepidermis,formsashieldagainstinvadersandse

3、creteschemicalsthatkillpotentialinvaders•Youshedbetween40-50thousandskincellseveryday!TheFirstLineofDefense:MucusandCilia•Asyoubreathein,foreignparticlesandbacteriabumpintomucusthroughoutyourrespiratorysystemandbecomestuck•Hair-likestructurescalledciliasweepthismucusin

4、tothethroatforcoughingorswallowingDon’tswallowedbacteriahaveagoodchanceofinfectingyou?TheFirstLineofDefense:SalivaWhat’sthefirstthingyoudowhenyoucutyourfinger?•Salivacontainsmanychemicalsthatbreakdownbacteria•Thousandsofdifferenttypesofbacteriacansurvivethesechemicals,

5、howeverThinkofthehumanbodyasahollowplastictube…Thefoodisdigestedwithintheholeinthetube,butitneveractuallyentersintothesolidplasticmaterial.TubeinnersurfaceTubeoutersurfacePlasticinterior~DigestiveSystem~~Skin~~Body~TheFirstLineofDefense:StomachAcid•Swallowedbacteriaare

6、brokendownbyincrediblystrongacidsinthestomachthatbreakdownyourfood•Thestomachmustproduceacoatingofspecialmucusorthisacidwouldeatthroughthestomach!Escherichiacoliiscommonandplentifulinallofourdigestivetracts.Whyareweallnotsick?•Thesebacteriaaretechnicallyoutsidethebodya

7、ndaidindigestingmaterialwecannot•OnlyifE.ColiareintroducedinanunnaturalmannercantheybreakthroughthefirstlineofdefenseandharmusTheSecondLineofDefense:WhiteBloodCells•Ifinvadersactuallygetwithinthebody,thenyourwhitebloodcells(WBCs)begintheirattack•WBCsnormallycirculateth

8、roughouttheblood,butwillenterthebody’stissuesifinvadersaredetectedWhiteBloodCells:Phagocytes•Thesewhitebloodcellsarer