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Immunity :

Immunity : . The Immune system plays a role in combating infection, creating inflammation (& consequently heart disease), controlling (or not) cancer and in auto-immune diseases.

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Immunity :

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  1. Immunity : The Immune system plays a role in combating infection, creating inflammation (& consequently heart disease), controlling (or not) cancer and in auto-immune diseases. Immune modulator molecules or cytokines and leukotrienes which are produced by the immune system can interact with most cells of the body The immune system consists of organs, vessels, and cells that can be specific to a particular organism or “antigen” or non-specific. Some cells can identify foreign or damaged cells or microbes, others can kill in various ways.

  2. Organs and cells of the Immune System • Organs of the immune system include the bone marrow where white blood cells are differentiated, the lymphoid organs (spleen, tonsils, appendix, lymph nodes) where lymphocytes live, and he lymphatic vessels where lymph is found. • Cells of the immune system include lymphocytes (many types), other white blood cells (neutrophils, basophils, and eosinophils), macrophages (found everywhere), and other dendritic cells.

  3. Non-Specific immunity

  4. White Blood cells • Lymphocytes of the immune system in transit (20%) • Macrophages (the “eaters” of the immune system in transit) as monocytes (8%) • Neutrophils one of he best “eaters” of bacteria (70%) They leave blood vessels under signals from other immune system cells like macrophages • Other cells of the immune system such as basophils and eosinophils which has granules in their cytoplasm they can exocytose containing heparin and histamine (basophils) or toxic lysosome contents (eosinophils)

  5. The Lymphatic System The lymphatic system is the body’s surveillance system . It is made up of lymph nodes connected by vessels that have lymph flowing in them, and lymphoid organs.

  6. Lymph enters the vessels in the tissues all over the body as more plasma leaves arteries than enters veins.

  7. Lymph vessels have valves to prevent backflow

  8. In addition to lymph nodes there are other lymphoid tissues that guard entry or transition such as tonsils or appendix

  9. The spleen filters blood through lymphocytic tissue and also through screening for red blood cell damage or decay

  10. Thymus is a gland that is larger in children--- it matures T-cells

  11. Lymph nodes have entry and exit vessels and pathways where the fluid flows through large numbers of lymphocytes

  12. Lymphocytes: cells of the specific immune systemSurveillance, intelligence, antibody production and cytotoxic killers • Three main types of lymphocytes are T-cells and B-cells. • 10% are NK cells • 15% are B-cells make antibodies • 80% T-cells are cytotoxic killer cells, control of the immune response (suppressor T-cells), and the coordinators of the immune response (helper T-cells)

  13. Lymphocytes are made in bone marrow from stem cells and matured either in bone marrow (B-cells) or in the thymus (T-cells)

  14. Membrane Proteins and Lymphocytes All cells make proteins called major histocompatitibity proteins (MHC) that pick up fragments of peptides and places them in the membrane. This allows the immune system to recognize that the cell is (a) self and (b) normal, not infected, malignant or damaged.

  15. Membrane Proteins and Lymphocytes Some cells, such as macrophages, can eat bacteria or other microbes and break them up. They make MHC Class II proteins which can “present” the antigen in the membrane for lymphocytes to “see” it.

  16. Lymphocytes (1) Natural Killer cells

  17. Lymphocytes (2) Antibody producing B-cells B-cells have receptors (IgD) in their membranes where they can bind antigens. An antigen is a small fragment of a protein or lipoprotein from an organism or other invader (or from a cat saliva protein) The B-cell takes in the antigen and makes an MHC class II protein containing the antigen that can then be “presented” to a helper T-cell which will confirm that it is an invader or other undesirable

  18. B-cell Activation to make antibodies, another view

  19. Antibodies: what can they do?

  20. Figure 14.13c

  21. Figure 14.13e

  22. Table 14.2

  23. Figure 14.14

  24. Lymphocytes (3) T-cells • There are 2 main types of T-cells identified by membrane markers CD4 and CD8. • All T-cells and B-cells make memory cells • CD8 T-cells are killer T-cells and suppressor T-cells • CD4 T-cells are Helper T-cells

  25. CD8 T-cells

  26. CD8 cells activation

  27. CD4 T-cells

  28. CD4 cell activation

  29. Helper T-cells coordinate the immune response

  30. Overview of the Immune Response

  31. Fig. 22-25, p. 796

  32. Response to infection

  33. How Vaccines work • Exposure to a part of an organism, an attenuated organism or a tiny dose of live organism stimulates the immune system to form memory cells • Some response needs more than one exposure to get good coverage (examples are hepatitis B, human papilloma virus)

  34. Fig. 22-22a, p. 794

  35. Fig. 22-22b, p. 794

  36. Mechanism of Allergy and Anaphylaxis Fig. 22-26, p. 801

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