The Lymphatic System And Immunity1


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The Lymphatic System And Immunity1

  1. 1. The Lymphatic System and Immunity
  2. 2. Introduction <ul><li>Pathogens: microorganisms responsible for human and animal diseases </li></ul><ul><ul><li>Bacteria </li></ul></ul><ul><ul><li>Viruses </li></ul></ul><ul><ul><li>Fungi </li></ul></ul><ul><ul><li>Parasites </li></ul></ul><ul><li>Lymphatic system </li></ul><ul><ul><li>Keeps us alive and healthy </li></ul></ul>
  3. 3. Defenses <ul><li>First line of Defense </li></ul><ul><li>- Skin and the linings of the respiratory, digestive, and urinary systems </li></ul><ul><li>- Involves chemical deterrents like a) skin , for instance produces a slightly acidic secretion that impairs bacterial growth. </li></ul><ul><li>b) stomach lining releases hydrochloric acid that destroys ingested bacteria. </li></ul><ul><li>c) saliva contains an enzyme that dissolves the cell wall of bacteria, killing them. </li></ul>
  4. 4. Defenses Cont <ul><li>Second line of defense </li></ul><ul><li>chemical and cellular agents that take up the battle from this point </li></ul><ul><li>A cut or abrasion, for instance, results in the inflammatory response. </li></ul><ul><li>Characteristics : 1) Redness, 2)swelling, 3)pain, 4) Heat </li></ul>
  5. 6. Chemical substances <ul><li>Histamine is a chemical released by injured tissue causes arterioles in the damaged area to expand or dilate thereby allowing more blood to flow into the region. </li></ul><ul><li>Another chemical safe guard not part of the inflammatory response, is a group of small proteins known as the interferons. </li></ul><ul><li>Interferon's are released from cells infected by viruses and they help to halt the spread of viruses from one cell to another </li></ul>
  6. 7. The Immune System <ul><li>3rd Line of Defense </li></ul><ul><li>Lymphocytes are a key component of the immune system. They circulate in the blood and lymph and also take up residence under linings of the respiratory and digestive systems. Many also reside in the spleen, thymus,lymph nodes, and tonsils, known as lymphoid organs </li></ul>
  7. 8. Organization of Lymphatic System <ul><li>3 components </li></ul><ul><ul><li>Lymphatic vessels </li></ul></ul><ul><ul><li>Fluid (lymph) </li></ul></ul><ul><ul><li>Lymphoid organs </li></ul></ul>
  8. 9. Functions of Lymphatic System <ul><li>Production, maintenance, distribution of lymphocytes </li></ul><ul><ul><li>Respond to presence of: </li></ul></ul><ul><ul><ul><li>Invading pathogens </li></ul></ul></ul><ul><ul><ul><li>Abnormal body cells (virus-infected cells, cancer cells) </li></ul></ul></ul><ul><ul><ul><li>Foreign proteins (toxins released by bacteria) </li></ul></ul></ul><ul><li>Return of fluid and solutes from peripheral tissues to blood </li></ul><ul><li>Distribution of hormones, nutrients, and waste products from tissues of origin to general circulation </li></ul>
  9. 10. Types of Lymphocytes <ul><li>T cells (Thymus dependent) </li></ul><ul><ul><li>80% of circulating lymphocytes </li></ul></ul><ul><ul><li>Cytotoxic T cells </li></ul></ul><ul><ul><ul><li>Directly attack foreign cells or body cells infected by viruses (cell-mediated immunity) </li></ul></ul></ul><ul><ul><li>Helper T cells </li></ul></ul><ul><ul><ul><li>Stimulate activities of both B and T cells </li></ul></ul></ul><ul><ul><li>Suppressor T cells </li></ul></ul><ul><ul><ul><li>Inhibit both T and B cells </li></ul></ul></ul>
  10. 11. Types of Lymphocytes <ul><li>B cells (Bone-marrow derived) </li></ul><ul><ul><li>10-15% circulating lymphocytes </li></ul></ul><ul><ul><li>Plasma cells </li></ul></ul><ul><ul><ul><li>Responsible for production and secretion of antibodies (immunoglobulins) </li></ul></ul></ul><ul><ul><li>Responsible for antibody-mediated immunity </li></ul></ul><ul><li>NK cells (Natural Killer) </li></ul><ul><ul><li>5-10% </li></ul></ul><ul><ul><li>Attack foreign cells, normal cells infected with viruses, and cancer cells </li></ul></ul><ul><ul><li>Immunological surveillance </li></ul></ul>
  11. 12. Lymphoid Nodules <ul><li>Masses of lymphoid tissue w/o a capsule </li></ul><ul><ul><li>Increase and decrease size depending on # lymphocytes present </li></ul></ul><ul><li>Found beneath epithelial lining of organs in: </li></ul><ul><ul><li>Respiratory system </li></ul></ul><ul><ul><li>Digestive system </li></ul></ul><ul><ul><ul><li>Tonsils </li></ul></ul></ul><ul><ul><ul><li>Peyer’s patches </li></ul></ul></ul><ul><ul><li>Urinary system </li></ul></ul>
  12. 13. Lymphoid Organs: Lymph Nodes
  13. 14. Lymphoid Organs: Thymus
  14. 15. Lymphoid Organs: Spleen
  15. 16. The Lymphatic System and Body Defenses <ul><li>Nonspecific Defenses </li></ul><ul><ul><li>Do not distinguish one threat from another </li></ul></ul><ul><ul><li>Physical barriers </li></ul></ul><ul><ul><li>Phagocytic cells </li></ul></ul><ul><ul><li>Immunological surveillance </li></ul></ul><ul><ul><li>Interferons </li></ul></ul><ul><ul><li>Complement </li></ul></ul><ul><ul><li>Inflammation </li></ul></ul><ul><ul><li>Fever </li></ul></ul><ul><li>Specific Defenses </li></ul><ul><ul><li>Protect against particular threats </li></ul></ul><ul><ul><li>Develop after birth </li></ul></ul><ul><ul><li>Dependent on activity of lymphocytes </li></ul></ul><ul><ul><li>B cells </li></ul></ul><ul><ul><li>T cells </li></ul></ul>
  16. 19. Macrophage
  17. 20. Apoptosis and Macrophages
  18. 22. Immune System
  19. 23. Properties of Immunity <ul><li>Specificity </li></ul><ul><li>Versatility </li></ul><ul><li>Memory </li></ul><ul><li>Tolerance </li></ul>
  20. 24. Overview of Immune Response
  21. 25. Specific Defense: The Immune Response <ul><li>Respond to specific antigens </li></ul><ul><li>T cells </li></ul><ul><ul><li>Cell-mediated immunity (cellular immunity) </li></ul></ul><ul><ul><li>Provide defense against abnormal cells and pathogens in living cells </li></ul></ul><ul><li>B cells </li></ul><ul><ul><li>Antibody-mediated immunity (humoral immunity) </li></ul></ul><ul><ul><li>Provide a defense against antigens and pathogens in body fluids </li></ul></ul>
  22. 26. Forms of Immunity <ul><li>Either innate or acquired </li></ul><ul><li>Innate </li></ul><ul><ul><li>Genetically determined </li></ul></ul><ul><li>Acquired </li></ul><ul><ul><li>Active or Passive </li></ul></ul><ul><ul><ul><li>Active Immunity </li></ul></ul></ul><ul><ul><ul><ul><li>Naturally acquired immunity </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Induced active immunity </li></ul></ul></ul></ul><ul><ul><ul><li>Passive Immunity </li></ul></ul></ul><ul><ul><ul><ul><li>Induced passive immunity </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Natural passive immunity </li></ul></ul></ul></ul>
  23. 28. T Cells <ul><ul><li>Once activated, T cells divide and differentiate in to cells with specific function in immune response </li></ul></ul><ul><ul><ul><li>Cytotoxic T cells </li></ul></ul></ul><ul><ul><ul><li>Helper T cells </li></ul></ul></ul><ul><ul><ul><li>Memory T cells </li></ul></ul></ul><ul><ul><ul><li>Suppressor T cells </li></ul></ul></ul>
  24. 31. Cytotoxic T Cells <ul><li>Responsible for cell-mediated immunity </li></ul><ul><li>Track down and attack bacteria, fungi, protozoa, or foreign transplanted tissue </li></ul><ul><li>Also called Killer T cells </li></ul>
  25. 32. Helper T Cells <ul><li>Activated by exposure to antigens bound to Class II MHC proteins </li></ul><ul><li>Activated  divide to produce </li></ul><ul><ul><li>Active Helper T cells and memory cells </li></ul></ul><ul><li>Release variety of cytokines that: </li></ul><ul><ul><li>Coordinate specific and nonspecific defenses </li></ul></ul><ul><ul><li>Stimulate cell mediated and antibody-mediated immunity </li></ul></ul>
  26. 33. Memory T Cells <ul><li>During cell division for both cytotoxic and helper T cells, some develop into memory cells </li></ul><ul><li>Remain in reserve </li></ul><ul><li>If same antigen attacks 2 nd time, memory T cells immediately differentiate into cytotoxic T cells and helper T cells </li></ul><ul><ul><li>Allows for more rapid and effective immune response </li></ul></ul>
  27. 34. Suppressor T Cells <ul><li>When activated, depress responses of other T and B cells </li></ul><ul><li>Does not occur immediately </li></ul><ul><ul><li>Takes much longer for these cells to become activated </li></ul></ul><ul><ul><li>Act after initial immune response </li></ul></ul>
  28. 35. B Cells and Antibody-Mediated Immunity: B Cell Activation <ul><li>Each B cell carries its antibody molecules in its cell membrane </li></ul><ul><li>When bacterium first enters the body, B cells programmed to respond to the unique proteins found in the bacterium’s cell membrane bind to it </li></ul>
  29. 36. B Cell Activation <ul><li>Activated B cells divide several times </li></ul><ul><ul><li>Produce daughter cells that differentiate into: </li></ul></ul><ul><ul><ul><li>Plasma cells </li></ul></ul></ul><ul><ul><ul><ul><li>Synthesize and secrete large numbers of antibodies on surface of sensitized B cells </li></ul></ul></ul></ul><ul><ul><ul><li>Memory cells </li></ul></ul></ul><ul><ul><ul><ul><li>Similar to memory T cells </li></ul></ul></ul></ul><ul><ul><ul><ul><li>If exposed to same antigen, will differentiate into plasma cells </li></ul></ul></ul></ul>
  30. 39. Classes of Antibodies (Immunoglobins Igs) <ul><li>IgG </li></ul><ul><ul><li>Largest and most diverse </li></ul></ul><ul><ul><li>Resist many viruses, bacteria, bacterial toxins </li></ul></ul><ul><ul><li>Can cross placenta </li></ul></ul><ul><ul><ul><li>What type of immunity is that? </li></ul></ul></ul><ul><li>IgM </li></ul><ul><ul><li>Circulate; attack bacteria </li></ul></ul><ul><li>IgA </li></ul><ul><ul><li>Found in exocrine secretions </li></ul></ul><ul><ul><ul><li>Ex? </li></ul></ul></ul><ul><ul><li>Attack pathogens before they enter the body </li></ul></ul><ul><li>IgE </li></ul><ul><ul><li>When bound to antigen, stimulates basophils and mast cells to release chemicals to stimulate inflammation </li></ul></ul><ul><li>IgD </li></ul><ul><ul><li>Attached to B cell and involved in their activation </li></ul></ul>
  31. 40. The Complement System
  32. 41. Antibody Function <ul><li>Neutralization </li></ul><ul><li>Agglutination and Precipitation </li></ul><ul><li>Activation of a complement </li></ul><ul><li>Attraction of phagocytes </li></ul><ul><li>Enhancement of phagocytosis </li></ul><ul><li>Stimulation of inflammation </li></ul>
  33. 42. Primary and Secondary Responses to Antigen Exposure