KAAP310 Quiz: Chapter 21 Notes

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University of Delaware
Kinesiology & Appl Physiology
Rose William

Ch. 21 Notes: Immune System – resistance to disease I. Innate Defenses (non-specific) 1. Surface/External Body: Skin & mucous membranes, 1 defense • Physical barriers to entry o Respiratory system (mucus-coated hairs, cilia of upper respiratory tract) o Surface barrier destroyed from cut?  2 defense • Protective chemicals on skin & mucous membranes o Acidity of skin and secretions (inhibits growth) o Enzymes (ex: lacrimal fluid) kill microorganisms o Defensins (antimicrobial peptides) o Other: Ex – lipids in sebum = toxic 2. Internal defenses: Cells/Chemical defenses, 2 defense; Inhibit spread of invaders, **inflammation • Phagocytosis – adhere to invader, cytoplasmic extension bind to and engulf particle • Opsonization marks pathogens = coating by complement PROs or antibodies ▪ Pathogens killed by acidifying & digesting with lysosomal enzymes ▪ ‘Helper T Cells’ = release respiratory burst which kill pathogens resistant to LY enzymes • Release free radicals • Oxidizing chemicals • Increase pH o Neutrophils = most abundant but die fighting (phagocytic - exposed to infectious material) o Macrophages = develop from monocytes, **MAIN phagocytic cells • Natural killer (NK) cells (non-phagocytic) o Attack cells lacking “self” surface receptors, potent chemicals  inflam response ▪ Kill virally-infected & cancerous cells before adaptive defenses kick in • Inflammation (tissue injured, dispose of debris/pathogens, alert adaptive immune system) o Signs: heat, redness, swelling, pain (sometimes impairment of function) • Fever = abnormally high body temp o “Hypothalamic thermostat” resets to a higher temp o Heat production & heat conservation INCREASE (pyrogens) o Higher temp may lead to greater biochemical activity of defensive systems (but also of pathogens?) o Higher temp may cause sequestration of Fe & Zn which may slow bacterial growth Antimicrobial defenses • Interferon = small cytokines produced by leukocytes; immune modulating PROs o Interfere with viral replication o Produce PROs that block viral reproduction and degrade viral RNA; activate NK cells • Complement o System of ~20 plasma PROs which, when activated, can kill target cells and can help activate other defensive systems o Classical – antibodies bind to invading organisms and to complement components o Alternative – activation of C3 o Lectin (PROs produced by the liver) - bind to mannose (sugar) residues found on surface of many pathogens o MAC = membrane attack complex II. Adaptive Defenses (specific and systemic aka not restricted to initial site) • MHC cells = major histocompatibility proteins • Antigens = antibody generators = mobilize adaptive defenses and provoke immune response o Complete (lipids, nucleic acids, foreign PROs) ▪ Immunogenicity: ability to stimulate proliferation of specific lymphocytes ▪ Reactivity: ability to react with activated lymphocytes and antibodies released by immunogenic reactions o Haptens (incomplete); poison ivy, animal dander, detergents, cosmetics ▪ Cause immune system to mount harmful attack  Cells of adaptive immune system • Lymphocytes o B cells – humoral immunity (“bone marrow” lymphocytes); make antigen receptors ▪ Extracellular pathogens (bacteria, parasites, fungi) ▪ Effector cells: plasma cells o T cells – cellular immunity (subtypes: helper T, cytotoxic T, regulatory T, memory T…) ▪ Intracellular pathogens (effectors: virus-infected cells and cancer cells) ▪ + selection – capable of recognizing MHC restriction (failure to recognize = cell suicide) ▪ - selection – must NOT recognize self-antigens; failure to recognize = survival o Maturation ▪ Immunocompetence – lymph recognizes 1 specific antigen by binding to it (ONLY 1) ▪ Self-tolerance – lymphocytes unresponsive to own antigens (do not attack own body) • Antigen-presenting cells (APCs) – don’t respond to specific antigens, engulf antigens o Dendritic cells = connective tissues/epidermis; phagocytize pathogens, present antigens to T cells ▪ **key link b/w innate and adaptive immunity; **most effective antigen presenter o Macrophages = connective tissues/lymphoid organs o B cells 1. Humoral Immune Response (antibody mediated) – has extracellular targets • Clonal selection of B cells  usually plasma cells • Only the B cell(s) that recognize the antigen are selected for proliferation (mitosis makes copies) and differentiation (make specialized daughter cells of plasma cells and memory B cells) o Role of plasma cells o Role of memory B cells: stronger, faster response to future exposures to same antigen st • Primary immune response: cell proliferation/differentiation upon 1 antigen exposure (3-6 da
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