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NOTES: CH 43, part 2 – Immunity; Immune Disruptions (43.3-43.4)

NOTES: CH 43, part 2 – Immunity; Immune Disruptions (43.3-43.4). Activated B & T Lymphocytes produce:. ● CELL-MEDIATED IMMUNE RESPONSE : involves specialized T cells destroying infected host cells ● HUMORAL IMMUNE RESPONSE : occurs in the blood & lymph ; involves activated B cells

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NOTES: CH 43, part 2 – Immunity; Immune Disruptions (43.3-43.4)

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  1. NOTES: CH 43, part 2 – Immunity; Immune Disruptions(43.3-43.4)

  2. Activated B & T Lymphocytes produce: ● CELL-MEDIATED IMMUNE RESPONSE: involves specialized T cells destroying infected host cells ● HUMORAL IMMUNE RESPONSE: occurs in the blood & lymph; involves activated B cells **BOTH responses are triggered by activated helper T cells!

  3. T CELLS and the CELL-MEDIATED IMMUNE RESPONSE * T cells are activated when an antigen-presenting cell displays a foreign antigen antigen T cell! Antigen Presenting Cell (APC)

  4. T CELLS and the CELL-MEDIATED IMMUNE RESPONSE Example: 1) a macrophage engulfs and digests a pathogen 2) the macrophage displays the antigens on its cell membrane using class II MHC.

  5. 3) the macrophage encounters a HELPER T CELL with the appropriate antigen receptor  activates T cell 4) activated helper T cell stimulates B cell to produce antibodies specific for the displayed antigen

  6. **Activated TH cells secrete CYTOKINES: -CYTOKINES = factors that stimulate other lymphocytes; -Interleukin-2 (IL-2): stimulates B cells to differentiate into antibody-secreting plasma cells(humoral response) and induces cytotoxic T cells to become active killers (cell-mediated response!). -Interleukin-1 (IL-1): secreted from APCs; promotes activation of helper T cells w/same MHC-antigen receptors.

  7. **Other T cells: CYTOTOXIC T CELLS: •  recognize nonself antigens on cancer cells or virus-infected cells; •  antigen-activated TC cells kill body cells that are infected by pathogens (or are cancerous). • TC cells recognize and bind to antigen-class I MHC markers (host cells display antigens with class I MHC molecules); • (TC cells have special plasma membrane proteins called CD8, which have an affinity for class I MHC molecules…remember that class I MHC is found in all nucleated body cells)

  8. Cytotoxic T Cell Response: -cytotoxic T cells then bind to the surfaces of the antigen-bearing cells, and release a protein (PERFORIN) that cuts openings in these cells, causing them to burst (LYSE)

  9. CELL-MEDIATED IMMUNE RESPONSE:

  10. CELL-MEDIATED IMMUNE RESPONSE:

  11. Before…..…..After A fully intact cancer cell surrounded by the immune systems killer t-cells. The cancer cell is surrounded and attacked by  the killer T-Cells of the immune system. Scanning electron microscope pictures shows killer t-cells attacking the cancer cell. Notice the tentacles of the cancer cell. Notice how the cancer is completely flattened and totally destroyed. During the killing process, granules in a T-Cell fuse with the cell membrane and release units of the protein PERFORIN. These combine to form pores in the target cell membrane. Thereafter fluid and salts enter so that the target cell eventually bursts.

  12. CELL-MEDIATED IMMUNE RESPONSE:

  13. T cells… *Some T cells do not respond to the antigen on the first exposure…they remain as MEMORY T CELLS; upon a second exposure to the same antigen, they respond quickly

  14. B CELLS and the HUMORAL IMMUNE RESPONSE * B cells are activated when they encounter (1) an antigen in the blood or lymph that fits its antigen receptors, & (2) an activated helper T cell that recognizes the same antigen

  15. B CELLS and the HUMORAL IMMUNE RESPONSE Example: 1) a B cell encounters an antigen in the blood or lymph that fits its antigen receptors…internalizes & displays the antigen; 2) B cell encounters a helper T cell bearing receptors for the same displayed antigen…this interaction activates the B cell!

  16. 3) some activated B cells specialize into PLASMA CELLS (antibody-producing cells) *(antibodies react against the antigen that stimulated their production!)…more on this later 4) some activated B cells differentiate into MEMORY B CELLS (respond to subsequent exposures)

  17. HUMORAL IMMUNE RESPONSE:

  18. HUMORAL IMMUNE RESPONSE:

  19. HUMORAL IMMUNE RESPONSE:

  20. HUMORAL & CELL-MEDIATED IMMUNE RESPONSE:

  21. TYPES OF ANTIBODIES ● antibodies are soluble proteins called IMMUNOGLOBULINS(Ig) ● 5 major types of antibodies: IgG, IgA, IgM, IgD,andIgE.

  22. Antibody Structure and Function: ● epitope: a localized region on an antigen’s surface that is recognized by antibodies ● structure:

  23. ANTIBODY ACTIONS ● antibodies work by: 1) NEUTRALIZATION: bind directly to antigens on surface of pathogen (i.e. virus)…blocking its ability to bind to a host cell!

  24. ANTIBODY ACTIONS ● antibodies work by: 2) OPSONIZATION: binding to antigens on surface of bacteria…promotes phagocytosis by macrophages or neutrophils -cause them to clump together (AGGLUTINATION) or form insoluble masses (PRECIPITATION)

  25. AGGLUTINATION!

  26. ANTIBODY ACTIONS 3) activating COMPLEMENT PROTEINS -a group of proteins that work together to produce a variety of effects: ● attract phagocytes ● formation of a “Membrane Attack Complex” that ruptures foreign cell membranes ● coating the cells/viruses, making them more susceptible to phagocytosis

  27. ANTIBODY ACTIONS 4) stimulate changes in local areas that help prevent the spread of the antigens (i.e. promote inflammation)

  28. CLASSIFICATION OF IMMUNITY 1) ACTIVE IMMUNITY ● when the person produces an immune response (including memory cells) to the antigen ● a result of direct exposure to the antigen ● long-lasting (memory cells)

  29. ACTIVE IMMUNITY… • NATURALLY ACQUIRED ACTIVE IMMUNITY: person is directly exposed to the pathogen, develops a disease, and acquires immunity • ARTIFICIALLY ACQUIRED ACTIVE IMMUNITY: person receives a vaccine

  30. VACCINES… **A VACCINE consists of bacteria or viruses that have been weakened or killed so they a cannot cause a serious infection; or could include a toxin that has been chemically altered to destroy its toxic effects -includes antigens that stimulate a primary immune response but does not produce the severe symptoms of disease

  31. 2) PASSIVE IMMUNITY ● person receives antibodies produced by another individual ● since the person does not produce the immune response themselves, this is short-term only (as long as the antibodies remain in the blood) ● the person remains vulnerable to the antigen if exposed at a later date

  32. PASSIVE IMMUNITY • NATURALLY ACQUIRED PASSIVE IMMUNITY: fetus acquires limited immunity from mother through placenta and/or breast milk (colostrum) ARTIFICIALLY ACQUIRED PASSIVE IMMUNITY: person receives an injection of antiserum collected from a person who has already developed immunity against a particular disease

  33. TRANSPLANTATION and TISSUE REJECTION ● TISSUE REJECTION REACTION: when a transplant recipient’s immune system reacts against the donated tissue/organ

  34. ● to minimize tissue rejection: • match donor and recipient tissues use immunosuppressive drugs (help with transplant acceptance, but may increase the recipient’s risk of infection)

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