17 Unit 1 Chapter 17. 17 Unit 1 Innate Immunity- fast, non-specific and no memory Barriers, pH...
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Transcript of 17 Unit 1 Chapter 17. 17 Unit 1 Innate Immunity- fast, non-specific and no memory Barriers, pH...
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The Lymphatic System The Lymphatic System & Immunity& Immunity
The Lymphatic System The Lymphatic System & Immunity& Immunity
Chapter 17
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ImmunityImmunityImmunityImmunity
• Innate Immunity- • fast, non-specific and no memory
Barriers, pH extremes, Phagocytes & NK cells, fever, inflammation, complement, interferon
• Adaptive Immunity• Slower, specific & has a memory
Lymphocytes: T-cells & B-cells
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Lymphatic SystemLymphatic SystemLymphatic SystemLymphatic System
• Lymphatic tissue – reticular connective tissue containing lymphocytes
• Bone marrow• Lymph- interstitial fluid in lymphatic vessels• Returns excess filtration from capillaries- to
circulation • Transport dietary lipids• Maintenance & distribution- lymphoid organs• Filter bacteria and help active defenses
Figure 17.1Figure 17.1
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Lymphatic VesselsLymphatic VesselsLymphatic VesselsLymphatic Vessels
• Begin at lymphatic capillariesSlightly larger than blood capillariesOverlapping cells like one-way valvePressure will force fluid in
• Merge to form larger & larger vesselsThin walled and more valves than veins
• Periodically have lymph nodesLymphocytes in capsuled structure
thoracic duct L subclavian veinat junction with jugular
R. lymphatic duct R. subclavian vein
Figure 17.2aFigure 17.2a
Figure 17.2bFigure 17.2b
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Lymphatic flowLymphatic flowLymphatic flowLymphatic flow
• From tissue to veins• Pumped by muscle & respiratory
pumps like venous return
Figure 17.3Figure 17.3
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Lymphatic OrgansLymphatic OrgansLymphatic OrgansLymphatic Organs
• Primary lymphatic organs- stem cells divide & develop into mature B & T-cellsRed bone marrow & thymus
• Secondary organs: immune responses occurLymph nodes, spleen & lymphatic
nodules
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ThymusThymusThymusThymus
• Two lobed organ• Posterior to sternum, medial to
lungs & superior to heart• T-cells divide & mature
Self reactive cells are removed
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Lymph nodesLymph nodesLymph nodesLymph nodes
• Scattered throughout the bodyConcentrated near mammary glands,
axilla & groin
• Contain mature B-cells, T-cells dendritic cells and macrophages
• Filter lymph, trap foreign substancesMacrophages & lymphocytes destroy
most foreign substances
Figure 17.4Figure 17.4
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SpleenSpleenSpleenSpleen
• Between stomach & diaphragm• Contains blood filled venous sinuses
and RBCs, macrophages, lymphocytes plasma cells & granular leukocytes
• destroys worn or defective blood cells & platelets
• Stores platelets• attacks foreign substances in blood• Fetal Hemopoiesis
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Innate Immunity- Innate Immunity- BarriersBarriers
Innate Immunity- Innate Immunity- BarriersBarriers
• Skin: Physical & chemicalEpidermal structure & constant shedding
• Mucous membranes:Sticky mucus layer straps microbes, etc.
and cilia move it out • Fluids: tears, saliva, perspiration,
nasal secretionssDilute and antibacterial action
• Movement: flow of urine, defecation & vomiting
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Internal Defenses- Internal Defenses- ProteinsProteins
Internal Defenses- Internal Defenses- ProteinsProteins
• Interferons- interfere with viral reproduction in a cell
• Complement SystemEnhance other immune actionsBreak cell membranesAttract phagocytes Tag microbial cells for destruction
• Transferrins- bind iron & starve bacteria• Antimicrobial peptides: lyse microbes
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Internal Defenses-CellsInternal Defenses-CellsInternal Defenses-CellsInternal Defenses-Cells
• Phagocytes specialized to ingest microbes and cellular debrisNeutrophils Monocytes macrophages
• 5-10% of lymphocytes = Natural Killer (NK) CellsDestroy microbes & tumor cellsPresent in lymph nodes & red bone
marrow
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InflammationInflammationInflammationInflammation
• Response to tissue damageIndicated by redness, pain, heat &
swelling
1. damage mast cells, basophils & platelets release histamine
increased permeability & vasodilation in blood vessels
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Inflammation (Cont.)Inflammation (Cont.)Inflammation (Cont.)Inflammation (Cont.)
2. leakage of clotting proteins into tissue-Isolate bacteria behind clot
3. phagocytes attracted to siteNeutrophils & macrophages eat & die
4. pocket of dead cells = pusMoves to body surface or into cavity
& is cleared
Figure 17.5Figure 17.5
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FeverFeverFeverFever
• Abnormally high body temperatureNew set-point of thermoregulation
systemNormal temperature control action
with new set point.
• Stimulated by many toxins or internal signals : interleukin-1
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Adaptive ImmunityAdaptive ImmunityAdaptive ImmunityAdaptive Immunity
• Specifically directed against a particular type of invader
• Involves cell or antibody directed against a particular antigenAntigen can be any substance:
microbe, food, pollen, tissue
• Normally self–tolerant (does not attack normal body tissue)
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Maturation of T & B cellsMaturation of T & B cellsMaturation of T & B cellsMaturation of T & B cells
• From stem cells in red bone marrow
• B cells mature in bone marrow• T cells migrate to thymus• During maturation both make
particular proteins in plasma membranes = antigen receptors
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Types of ResponsesTypes of ResponsesTypes of ResponsesTypes of Responses
• Cell-mediated- T-cells attack directlyKiller T-cells
• Antibody-mediated- • B cells become plasma cells
produce specific antibodies
• Helper T cells aid both cell- and antibody-mediated responses
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Antigens & AntibodiesAntigens & AntibodiesAntigens & AntibodiesAntigens & Antibodies
• Major Histocompatability Complex (MHC) = self antigens on cells surfaceUnique to each individual
• Allows T-cells to recognize foreign material• Antigen triggers plasma cell to produce
antibodiesY-shaped protein with variable antigen binding
site on armsOther end triggers recognition by phagocyte
Figure 17.6aFigure 17.6a
Figure 17.6bFigure 17.6b
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Triggering Adaptive Triggering Adaptive ResponseResponse
Triggering Adaptive Triggering Adaptive ResponseResponse
• requires recognizing the foreign antigen
• B-ceils can find it anywhere• T-cells need presentation with MHC• Antigen presenting cells (APC) do this• APCs macrophages, dendritic cells & B
cells• In respiratory, GI, urinary, reproductive
tracts & lymph nodes
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Processing & Presenting Processing & Presenting AntigensAntigens
Processing & Presenting Processing & Presenting AntigensAntigens
• APC’s ingest & digest into fragments in vesicles
• Synthesize MHC & pack in vesicles• Two vesicles fuse
antigen fragments bind to MHC
• Antigen-MHC complex inserted into plasma membrane
• Presented to T-cells until a receptor matches & binds
Figure 17.7Figure 17.7
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Cell Mediated ImmunityCell Mediated ImmunityCell Mediated ImmunityCell Mediated Immunity
• T-ceils also need costimulatorInterleukin-2 (IL-2)
• Binding both response• T-cell begins rapidly dividing
Forms a clone of many recognizing cells• Helper T cells-
release IL2, attract phagocytes, stimulate macrophages & B cells
• Cytotoxic T cells – kill cellsWork against tumor cells transplanted cells &
infected cells• Memory T cells- hang around for years,
give rapid response
Figure 17.8Figure 17.8
Figure 17.9Figure 17.9
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B-cells and Antibody- B-cells and Antibody- Mediated ResponseMediated Response
B-cells and Antibody- B-cells and Antibody- Mediated ResponseMediated Response
• Hang out in lymph nodes• Respond to antigen (faster if
presented)• With IL-2 enlarge, divide and become a
clone of plasma cells• Plasma cells produce & release
antibodies that bind the antigen• Some remain as Memory B Cells
Ready to respond quickly if antigen met again
Figure 17.11Figure 17.11
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Antibody Class ActionsAntibody Class ActionsAntibody Class ActionsAntibody Class Actions
• Neutralizing antigen-Binds & neutralizes toxins
• Immobilizing bacteria• Agglutinating-
Connect pathogens to one another easier phagocytosis
• Activating complement• Enhancing phagocytosis
Binding attracts phagocytes
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Immunological MemoryImmunological MemoryImmunological MemoryImmunological Memory
• Long lasting antibodies & lymphocytes• Many sensitive memory cells • Much larger & quicker response next
time = Secondary Response• Primary response can be naturally
acquired• or artificially acquired by vaccination
Killed cells, isolated antigens, parts of viruses
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AgingAgingAgingAging
• Thymus atrophies• Fewer responsive T cells• Thus poorer B cell response• Poorer response to new
infection