Immune System Notes

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Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Immune System essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Immune System:

Introduction to the immune system

Vaccinations

NOTES NOTES IMMUNE SYSTEM INTRODUCTION TO THE IMMUNE SYSTEM osms.it/immune-system-introduction ▪ Includes organs, tissues, cells, molecules ▪ Protects from microorganisms, removes toxins, promotes inflammation, destroys tumor cells ▪ Two branches ▫ Innate, adaptive INNATE IMMUNE RESPONSE ▪ Nonspecific cells: phagocytes, natural killer (NK) cells; no immunologic memory ▪ “Feverishly” fast (minutes to hours) Noncellular components ▪ Physical, chemical barriers (e.g. lysozymes in tears, cilia in airways) ▪ Inflammation: stops spread of infection, promotes healing ▫ Four cardinal signs: redness, heat, swelling, pain ▪ Complement system: cascade of proteins; triggers inflammation, kills pathogens by cytolysis, tags cells for destruction ADAPTIVE IMMUNE RESPONSE ▪ Highly specific cells; immunologic memory, need priming ▪ Significantly slower, esp. initially (weeks) ▪ Clonal expansions: cells replicate ▪ Clonal deletion: cells die off after immune response; some survive as memory cells 372 OSMOSIS.ORG CELLS OF THE IMMUNE SYSTEM Leukocytes (white blood cells) ▪ Formed by hematopoiesis in bone marrow ▫ Starts with multipotent hematopoietic stem cells ▫ Cells develop into myeloid/lymphoid progenitor cells ▪ Myeloid cells: contribute to innate response ▫ Neutrophils: phagocytes, granulocytes, polymorphonuclear cells (nucleus segmented into 3–5 lobes); stain light pink/reddish-purple; most numerous leukocyte ▫ Eosinophils: phagocytes, granulocytes, polymorphonuclear cells (nucleus usually bilobed); stain pink with eosin; larger cells fight parasites ▫ Basophils: nonphagocytes, granulocytes, polymorphonuclear cells (nucleus bilobed/segmented); stain bluepurple with hematoxylin; aid in fighting parasites; granules contain histamine, heparin; involved in inflammatory response; least numerous leukocyte ▫ Mast cells: nonphagocytes, granulocytes; involved in inflammatory response ▫ Monocytes: phagocytes, antigenpresenting cells; release cytokines to recruit other cells; only circulate in blood; differentiate into macrophages/dendritic cells ▫ Dendritic cells: phagocytes, antigenpresenting cells; release cytokines to recruit other cells; circulate in lymph,
Chapter 44 Immunology: Immune System blood, tissue; consume large proteins in interstitial fluid; break bloodborne pathogens into small amino acid chains → move to lymph node → present antigens to T cells ▫ Macrophages: phagocytes, antigenpresenting cells; release cytokines to recruit other cells; stay in connective tissue, lymphoid organs; not in blood ▪ Lymphoid cells: contribute to the adaptive response (except NK cells) ▫ NK cells: contribute to innate response; complete development in bone marrow; large, contain granules; primarily target infected, cancer cells; kill target cells with cytotoxic granules (punch holes in target cell membranes by binding to phospholipids → enter cell, trigger apoptosis, programmed cell death) ▫ B cells: contribute to adaptive response; complete development in bone marrow; bind to specific antigens (antigen presentation not needed); capable of phagocytosis, antigen presentation; load antigens on major histocompatibility complex (MHC) II, display to T cells; T-cell activation → B cells mature into plasma cells; secrete lots of antibodies/ immunoglobulins (B cell receptors in secreted-form, mark pathogens for destruction → “humoral immunity”) ▫ T cells: contribute to adaptive response; complete development in thymus; responsible for cell-mediated immunity; bind to specific antigens (antigen presentation needed); naive T cells primed by antigen presenting cells (usually dendritic cells); generally categorized into CD4+, CD8+ T cells; CD4+ (helper) T cells secrete cytokines to coordinate immune response, only see antigens on MHC II; CD8+ (cytotoxic) T cells kill target cells, cells with antigens on MHC I Figure 44.1 Family tree of immune system cells. OSMOSIS.ORG 373
CLASSIFICATION OF IMMUNE CELLS Phagocytes ▪ Reach around pathogens with cytoplasm, swallowing whole (phagosome) ▪ Destroy some pathogens with cytoplasmic granules (phagosomes fuse with granules → phagolysosomes; pH in vesicle drops killing pathogens) ▪ Continue to swallow pathogens before oxidative burst → produces highly reactive oxygen (e.g. H2O2; destroys proteins, nucleic acids, killing pathogens, phagocyte) Granulocytes ▪ Contain granules in cytoplasm ▪ All cells (except mast cells) polymorphonuclear Antigen-presenting cells ▪ Present antigens to T cells Figure 44.3 Antigen-presenting cell (depicted here as dendritic cell) presenting an antigen to a T cell. Figure 44.2 Phagocyte activities. 374 OSMOSIS.ORG
Chapter 44 Immunology: Immune System VACCINES osms.it/vaccines ▪ Generate protective adaptive immune response against microbes by exposure to nonpathogenic forms/components of microbes ▫ Differs from passive immunity (body creates own antibodies) ▪ Administration: intramuscularly, intradermally, intranasally, subcutaneously, orally ▪ Immunoglobulin response depends on route, type of vaccine ▫ Intramuscular vaccinations → IgG ▫ Rotavirus vaccine (oral) → IgA ▪ Four main types of vaccines ▫ Live attenuated, inactivated (whole cell vaccines) ▫ Subunit, toxoid (fractionated vaccines) LIVE ATTENUATED VACCINES ▪ Attenuated → pathogen weakened (but still replicates) ▪ Measles, mumps, rubella, varicella (MMRV); rotavirus; smallpox; yellow fever INACTIVATED VACCINES ▪ Pathogen killed using heat/formalin ▪ Response humoral/antibody-mediated; no cellular immunity → ↓ response ▪ Hepatitis A; polio; rabies; influenza SUBUNIT VACCINES ▪ Contain immunogenic portions of pathogens (polysaccharides/proteins) ▪ Combination of proteins from different pathogens → conjugate subunit vaccines ▪ Polysaccharide vaccines ▫ T cell independent (only respond to protein antigens) ▫ Not effective in children < two years old ▫ Memory B cells never formed → repeated doses needed ▫ Haemophilus influenzae type B; hepatitis B; HPV; Bordetella pertussis (pertussis); Streptococcus pneumoniae; Neisseria meningitidis; Varicella zoster OSMOSIS.ORG 375
TOXOID VACCINES ▪ Against specific toxins (main cause of illness) ▪ Toxoid fixed/inactivated using formalin ▪ Often combined with subunit vaccines ▪ Tetanus, diphtheria, and pertussis (TDaP), diphtheria, tetanus, and pertussis (DTap) vaccine CONTRAINDICATIONS ▪ Moderate/severe infection ▪ Allergy to eggs/previous vaccines ▪ Guillain–Barré syndrome (vaccines against influenza, DTaP) ▪ Weakened immune system ▫ Pregnant (live attenuated vaccines) 376 OSMOSIS.ORG

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Immune System essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Immune System by visiting the associated Learn Page.