1
▪
Immunity
LymphaticSystemandImmunity
– Abilitytoresistanddefendagainstinfectiousorganismsandotherdamagingsubstances
– Resistance
• Abilityof bodytomaintainimmunity
▪
Immuneresponse
– Body’sreactiontoinfectiousagentsand otherabnormalsubstances
▪
Pathogens
– Microscopicorganismsthatcausedisease
• Viruses
• Bacteria
• Fungi
• Parasites
– Eachattacksin aspecific way
▪
Lymphaticsystem(lymphoid system)
– Protectsusagainstdisease
– Lymphaticsystemcellsrespondto
• Environmentalpathogens
• Toxins
• Abnormalbodycells,suchascancers
– Lymphocytes
• Partoftheimmuneresponse
• Identify,attack,anddevelopimmunitytospecificpathogens
▪
Immunesystem
– Immunity
• Theabilityto resist infectionanddisease
– Allbody cellsandtissuesareinvolvedin productionofimmunity
▪
ComponentsofLymphaticsystem
– Lymph
• Afluid similar to plasma but without plasma proteins
– Lymphaticvessels
• Carrylymphfromperipheraltissuestoveins
– Lymphoidtissuesandlymphoidorgans
• Scatteredthroughout body
– Lymphoidcells
– Lymphocytes,phagocytes,andother cells
▪
Lymphocytesareproducedin
– Redbonemarrowandthymus
▪
Lymphocytesareactivatedin
– Secondarylymphoidtissuesand organs
– Tonsils,MALT,lymphnodes,andspleen
▪
Lymphocyte andFluid CirculationthroughLymphaticVessels (blindpockets)
– Frombloodtointerstitialfluid
– Returnstovenousbloodthroughlymphaticvessels
– Lymph= interstitial fluidthat has entereda lymphaticvessel
3/1/25, 11:49 AM
Lymphatic System and Immunity
about:blank
1/7
2
▪
Lymphaticvessels(lymphatics)
– Carrylymph—interstitialfluidthathas enteredlymphaticvessels
• Fromperipheraltissuesto venoussystem
▪
Lymphaticcapillaries
– Closedat oneendratherthanformingatube
– One-wayvalve
Lymphocytes:Make up20–40 percentofcirculatingleukocytesMost arestored, not circulating
3/1/25, 11:49 AM
Lymphatic System and Immunity
about:blank
2/7
3
▪
Lymphoidtissues
– Connectivetissueswithmanylymphocytes
▪
Lymphoid nodules(inlymphoidorgans)
– Connectivetissuewithmanylymphocytes
– Germinalcentercontains dividinglymphocytes
– Foundin
• Lymphnodes
• Spleen
• Tonsils
• Mucosa-associatedlymphoidtissue(MALT)
– Reproductive
– Urinary
– Digestivetracts
3/1/25, 11:49 AM
Lymphatic System and Immunity
about:blank
3/7
4
▪
Lymphnodefunction
– Purifylymphbefore returntovenouscirculation
• Remove99percentofforeignantigens
▪
Lymphoidtissuesandlymphnodes
– Monitorperipheralinfections
– Respondbeforeinfectionsreachvital organs
▪
Lymphnodes
– Protectagainstpathogensindigestiveandrespiratorysystems
– Swellinresponsetoinfection
▪
Thymus
– EnsuresmaturationofTCells
– Thymosin- Promotesdevelopment andmaturationof Tcells
▪
FunctionsoftheSpleen
– Removalofabnormalbloodcells
– Storageofiron
– Immuneresponsesto antigensincirculatingblood
▪
Twotypesof immunity
– Innate(nonspecific)immunity
• Alwaysworks thesame wayagainst anytypeof invadingagent
• Developsduringexposure
– Adaptive(specific)immunity
• Protectsagainstspecificpathogens
• Dependsonactivitiesoflymphocytes
• Developsafterexposureto environmentalhazards
▪
Lymphocytes
– Bcells,Tcells,andNKcells
▪
Lymphocytedistribution
– Lymphocyteswanderthrough tissues
• Enterbloodvesselsorlymphaticsfortransport
▪
TcellsandB cells
▪
BegindevelopmentinRed Bone Marrow
▪
Movethroughoutbodytodefendalltissues
▪
Retaintheirabilitytodivide
3/1/25, 11:49 AM
Lymphatic System and Immunity
about:blank
4/7
5
▪
Innate(nonspecific)defenses
– Blockorattackany foreignsubstanceorpathogen
– Examples
• Physicalbarriers –skin,hair,sections,epithelium,sweat
• Phagocytes–Macrophage(Monocyte),Eosinophil,Neutrophil
• Immunesurveillance–NKcells
• Interferons–interferewithviralreplication
• Complement–proteinsthatare produced bytheliverthathelpfightinfections
• Inflammation–localizedresponsethattriesto limitspreadofinfection
• Fever–raisesbodytemperature toincrease metabolismofourcellsandfight
infection
▪
Phagocytes(MEN)
– Macrophages
• Largephagocyticcellsderivedfrommonocytes
• Throughoutbody
• Makeupmonocyte–macrophagesystem(reticuloendothelialsystem)
– Eosinophils(Microphage)
• Enterperipheraltissuestofightinfections
– Neutrophils(Microphage)
• Enterperipheraltissuestofightinfections
▪
Macrophages
– Engulfpathogenanddestroyit withlysosomalenzymes
– Bindtopathogensoothercellscandestroy it
– Destroypathogen by releasingtoxicchemicals
▪
Typesofmacrophages
– Fixedmacrophages
• Stayinspecific tissues
– Freemacrophages(wanderingmacrophages)
• Travelthroughoutbody
▪
Howdothephagocytesgettotheenemy(pathogen)?
– Margination
– Diapedesis(movethroughcapillarywalls)
– Chemotaxis(Attractedorrepelledbychemicals insurroundingfluids)
– Phagocytosis
• Find
• Adhere
• Ingest
• Digest
• Excrete(Presentation)
▪
Immunesurveillance
– Carriedoutbynaturalkiller(NK)cells
– ActivatedNKcells
• Identifyandadheretoabnormalcells
• Perforinsreleasedbyexocytosisformholesinabnormalcell’splasmamembrane,
causinglysis
– Cancercells
• Tumor-specificantigens
• Identifiedasabnormalby NKcells
– Viralinfectedcells
• Presentabnormalproteinsonplasmamembranes
• AllowsNK cellstoidentifyanddestroy them
3/1/25, 11:49 AM
Lymphatic System and Immunity
about:blank
5/7
6
▪
Cytokines
– Chemicalmessengersreleasedbytissuecells
– Interferons(IFNs)
▪
Triggerproductionofantiviralproteinsthatblockviral replicationinthe
cell
▪
Complementsystem
– Complement–specialproteinsproducedbytheliverthattravelinthebloodhelp
destroypathogens
– Killspathogenbycelllysis
– Enhancephagocytosis(opsonization)
– EnhancesInflammation(histamine release)
▪
Inflammation
– Localizedtissueresponsetoinjury
– Triggeredbyanystimulusthat killscellsor injurestissue
– Cardinalsignsandsymptomsof inflammation
• Redness-rubor
• Swelling-tumor
• Heat-calor
• Pain-dolor
▪
Productsofinflammation
– Necrosis
• Localtissuedestructionin areaof injury
– Pus
• Mixtureof debris, fluid,dead anddyingcells,andnecrotictissue
– Abscess
• Accumulationofpusinan enclosedspace
▪
Fever
– Pyrogens
• Proteins(producedbyothercellsandour owncells)thatcausethehypothalamus
toraisebodytemperature
• Abody temperature greater than 37.2ºC (99ºF)
▪
Increasesmetabolicrate
▪
Acceleratesdefenses
▪
Inhibitssomevirusesandbacteria
3/1/25, 11:49 AM
Lymphatic System and Immunity
about:blank
6/7
