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The Immune System
First lines of defense:
•Skin
•Mucus
•Stomach acid
•Digestive enzymes
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Innate Immunity•Phagocytic cells–Leukocytes (“white cells”)
–Lymphocytes (“lymph cells”)
–Macrophages (“big eaters”)–Natural killer cells (attack infected or cancerous body cells)
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Innate Immunity•Inflammation–Redness and swelling
•Interferon –Released by infected cells, signals neighboring cells to prepare for invasion
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Acquired Immunity•Lymphocytes–B cells and T cells
•Antibodies –Immunoglobulins
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Antigens are foreign molecules that elicit an immune response
Acquired Immunity
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Antigens are foreign molecules that elicit an immune response.
Acquired Immunity
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B cells have antigen receptors that recognize intact antigens.
B
Acquired Immunity
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T cells have antigen receptors for fragments of antigens.
B T
Acquired Immunity
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Each lymphocyte recognizes one and only one antigen.
B T
Acquired Immunity
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•Lymphocytes are made in the bone marrow
•B cells mature in the bone marrow
•T cells go to the thymus before maturing.
Acquired Immunity
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•Genes in lymphocytes are randomly, permanently rearranged to produce over ten million different antigen receptors
•The ones that react to “self” are destroyed.
Acquired Immunity
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Two kinds of immune response:
Humoral
Defends against toxins or pathogens outside of cells
Cell-mediated or cytotoxic
Destroys infected cells, cancer cells, and transplanted cells
Acquired Immunity
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Humoral Immune ResponseHere come the germs…
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Humoral Immune ResponseHere come the germs…
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Humoral Immune Response1. A macrophage or a dendritic cell engulfs one of the invading bacteria
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Humoral Immune Response1. A macrophage or a dendritic cell engulfs one of the invading bacteria.
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Humoral Immune Response2. The macrophage displays broken up bits of the antigen bound to a major histocompatibility complex (MHC).
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Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated
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Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated
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Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated
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Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated.
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Humoral Immune Response4. A B cell also recognizes the antigen and binds to it
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Humoral Immune Response4. A B cell also recognizes the antigen and binds to it
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Humoral Immune Response4. A B cell also recognizes the antigen and binds to it.
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Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
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Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
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Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
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Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
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Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
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Humoral Immune Response6. The activated B cell divides to make two kinds of cells:
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Humoral Immune Response-Plasma cells make antibodies
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Humoral Immune ResponsePlasma cells (effector cells) make antibodies
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Humoral Immune ResponseMemory cells wait for the next invasion.
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Humoral Immune Response7. Antibodies bind to antigens.
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Humoral Immune ResponseThere are four ways that antibodies work:
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Humoral Immune ResponseThere are four ways that antibodies work:
neutralization
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Humoral Immune ResponseThere are four ways that antibodies work:
neutralization
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Humoral Immune ResponseThere are four ways that antibodies work:
neutralization
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Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
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Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
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Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
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Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
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Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
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There are four ways that antibodies work:
opsonization
Humoral Immune Response
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
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Cell Mediated Immune Response
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Cell Mediated Immune ResponseHere come the germs…
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Cell Mediated Immune ResponseA cell is infected
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Cell Mediated Immune ResponseA cell is infected
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Cell Mediated Immune Response1. A cell is infected.
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Cell Mediated Immune Response2. Antigens are displayed on the cell surface bound to MHC.
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Cell Mediated Immune Response3. A cytotoxic T cell (“killer T cell”) binds to the antigens
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Cell Mediated Immune Response3. A cytotoxic T cell (“killer T cell”) binds to the antigens
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Cell Mediated Immune Response3. A cytotoxic T cell (“killer T cell”) binds to the antigens.
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Cell Mediated Immune Response4. Binding activates the T cell, which releases lytic enzymes.
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Cell Mediated Immune Response5. Lytic enzymes destroy the cell (“apoptosis”)
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Cell Mediated Immune Response5. Lytic enzymes destroy the cell (“apoptosis”)
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Cell Mediated Immune Response6. T cell can now attack other target cells.
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Cell Mediated Immune ResponseCancer cells will also display antigens that bind with killer T cells.
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Immunity in Health and Disease
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Immunity in Health and Disease
Active vs. passive immunity.
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Immunity in Health and Disease
Rejection of transplanted tissue
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Immunity in Health and Disease
Rejection of transplanted tissue
Graft vs. host reaction.
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Immunity in Health and Disease
Allergies
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Immunity in Health and Disease
Autoimmune diseases
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Immunity in Health and Disease
Immunodeficiency diseases