Immune System

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Immune System by Mind Map: Immune System

1. Innate Immunity (all animals): Rapid Response - Small receptors recognize traits shared by pathogens

1.1. Barrier defenses: skin, mucous membranes , secretions

1.1.1. Mucus traps/allows microbe removal, secretions hostile to microbes, low pH prevents bacterial growth

1.2. Internal Defenses: phagocytic cells, natural killer cells, antimicrobial proteins, inflammatory response

1.2.1. Phagocytosis using TLRs TLRs recognize molecular fragments of pathogens Neutrophils engulf and destroy pathogens Macrophages throughout the body Dendritic cells stimulate adaptive immunity – in tissues Eosinophils discharge destructive enzymes

1.3. Antimicrobial peptides , antiinflammatory response

1.3.1. Antimicrobial Peptides: Attack pathogens or impede their reproduction Interferon s interfere with viruses by inhibiting reproduction and help activate macrophages Complement system - 30 proteins in plasma, activated by pathogen surface substances to lyse cells & trigger inflammatory response

1.3.2. Inflammatory Response: local or systemic- fever; Septic shock - overwhelming inflammatory response Mast cells release histamine that triggers blood vessel dilation & increased permeable erythema & increased skin temperature Activated phagocytes release cytokines, signaling molecules that recruit neutrophils to site Enhanced blood flow delivers antimicrobial peptides accumulation of pus

2. Adaptive Immunity (vertebrates only): Slower Response - Array of receptors recognize traits specific to particular pathogens

2.1. Humoral Response: antibodies defend against body fluid infections

2.1.1. Antigens: foreign substances that elicit a response from B or T cell to bind via receptors specific to a given pathogen Antigen-presenting cells have class I & II MHC molecules onsurfaces Epitope: small accessible portion of antigen that binds to receptor

2.1.2. In opsonization, antibodies bind to antigens on bacteria, triggering phagocytosis

2.1.3. Antigen-antibody complexes may bind to a complement protein- triggers cascade of c omplement protein activation - lysis

2.2. Cell-Mediated Response: cytotoxic cells defend against body cell infections

2.2.1. Lymphocytes - stem cells in bone marrow T cells mature in the thymus - hunter/killer cells T cells destroy affected host cells B cells remain in bone marrow B cells give rise to cells that create antibodies, neutralize or eliminate toxins and pathogens in the blood and lymph specialized

2.3. Invertebrates: exoskeletons, enzymes break down bacterial cell walls, hemocytes, recognize bacteria and fungi by cell wall structures

3. Primary Response: first exposure to a specific antigen, selected B and T cells activate effector forms

4. Active immunity: develops naturally when pathogen invades the body and elicits a primary or secondary immune response

5. Passive immunity: immediate, short-term protection from one individual to another

5.1. IgG antibodies cross the placenta from mother to fetus, or IgA antibodies from mother to infant in breast milk

6. Secondary immune response: memory cells facilitate a faster/efficient response

7. Immune system disorders: • Allergies - exaggerated response to allergens • Autoimmune disease – lupus, Type I diabetes, RA, PsA, MS • Exertion & stress – negatively impact immune function • Immunodeficiency disease – AIDS

7.1. Human immunodeficiency virus infects helper T cells , persists despite immune response, high mutation rate that promotes antigen variation , untreated HIV infection avoids/abolishes the adaptive immune response