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The Immune Response

The Immune Response. The 3 rd line of defense (Adaptive or acquired immunity). Specific Defenses. The immune system Consists of a large number of cells that work together to respond to a specific microbe or foreign invader. Two properties

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The Immune Response

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  1. The Immune Response The 3rd line of defense (Adaptive or acquired immunity)

  2. Specific Defenses • The immune system • Consists of a large number of cells that work together to respond to a specific microbe or foreign invader. • Two properties • Specificity for particular foreign molecules (antigens) • Memory for previously encountered antigens

  3. Definitions (see Vocab sheet) • Antigens • Are foreign substances that trigger an immune response • Most are pathogens • Antibodies • Are proteins found in blood plasma that attach to one particular kind of antigen and mark it for destruction.

  4. Antigens • Antibodies HIV Virus Pollen

  5. Antibodies • Y-shaped proteins that bind foreign molecules (antigens) • Produced by a white blood cell called the B cell

  6. The immune response has two main parts: • Humoral – involving antibodies • Cell Mediated – involving white blood cells.

  7. The 4 cells involved in the immune response • Macrophages/Dendritic cells • Cytotoxic (Killer) T Cells • B Cells – Plasma and Memory cells • Helper T Cells (Effector cells) 3. 4.

  8. Humoral (antibody mediated) Response • Macrophages/dendritic cells phagocytose microbes. • Some of the digested material (antigen) is then displayed on the surface of the macrophage/dendritic cell. • This allows the immune system to recognize the invader and become activated. • The process is known as: Antigen Presentation

  9. T cells are floating in the circulation. They carry receptors on the surface of their cell that are complementary to the antigen being presented. • T helper cells (Th ) or effector cells recognize and bind to displayed antigen.

  10. This binding causes macrophages to release Interleukin I. • Interleukin I causes Th cells to release Interleukin II • Interleukin II stimulates division of Th cells and cytotoxic T cells, amplifying body response to infection.

  11. Interleukin II released by Th cells also activates B cells. • Activated B cells divide and develop in to Plasma cells that release Y shaped antibodies into the blood. • Antibodies will bind to a specific antigen (the one originally presented by macrophage)

  12. The binding of antibodies causes antigens to stick together, forming clumps that can be easily identified and destroyed by macrophages. • B cells also divide into memory cells which will be rapidly activated if presented with same antigen in the future.

  13. Cell Mediated Response • Th release Interleukin II activating cytotoxic T cells • Activated cytotoxic T cells destroy infected cells by puncturing their cell membranes. • CytotoxicT cells recognize antigens because they have complementary receptors on the surface of their cells.

  14. Both the T cell and B cell response are regulated by helper T cells. Both responses happen simultaneously. • Both B and cytotoxic T cells create memory cells.

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