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Outline. The Lymphatic System Lymph Vessels Lymphoid Organs Nonspecific Defenses Barriers Inflammatory Response Specific Defenses Antibodies T Cells Induced Immunity Active versus Passive Immunity Immunity Side Effects Allergies Blood Typing. The Lymphatic System.

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Outline

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  1. Lymph Transport & Immunity

  2. Outline • The Lymphatic System • Lymph Vessels • Lymphoid Organs • Nonspecific Defenses • Barriers • Inflammatory Response • Specific Defenses • Antibodies • T Cells • Induced Immunity • Active versus Passive Immunity • Immunity Side Effects • Allergies • Blood Typing

  3. The Lymphatic System • Consists of lymphatic vessels and the lymphoid organs • Three main homeostatic functions: • Lymphatic capillaries take up and return excess fluid to the bloodstream • Lacteals receive lipoproteins and transport them to the bloodstream • Helps defend body against disease

  4. Lymphatic System

  5. The Lymphatic Organs

  6. Lymphatic System • One-way system that begins with lymphatic capillaries • Take up fluid that has been diffused from, and not reabsorbed by, blood capillaries • Edema - Localized swelling due to accumulation of tissue fluid • Lymph flows one way • From a capillary to ever-larger lymphatic vessels • Finally to a lymphatic duct, which enters a subclavian vein

  7. Lymphoid Organs • Lymph Nodes - Capsule surrounding two distinct regions, cortex and medulla • Lymphocytes congregate in cortex when fighting off a pathogen • Macrophages concentrated in medulla - cleanse lymph • Lymph nodes named for their location

  8. Lymphoid Organs • Tonsils • Patches of lymphatic tissue located around the pharynx • First to encounter pathogens that enter via the nose and mouth • Spleen • Located in upper left region of abdominal cavity just beneath diaphragm • Cleanses blood

  9. Lymphoid Organs • Thymus Gland • Located along trachea behind the sternum in upper thoracic cavity • Produces thymic hormones • Red Bone Marrow • Origin for all types of blood cells • Area of maturation for most white blood cells

  10. Immune System • Nonspecific Defenses • Barriers to entry serve as mechanical barriers • Skin • Mucous membranes lining respiratory, digestive, and urinary tracts

  11. Nonspecific Defenses • Inflammatory Reaction • Damaged cells and mast cells release histamine and kinins • Capillaries dilate and become more permeable • Enlarged capillaries cause skin to redden • Swollen area and kinins stimulate free nerve endings causing pain

  12. Inflammatory Reaction • Neutrophils and monocytes migrate to the site of injury • Neutrophils and mast cells phagocytize pathogens • Monocytes differentiate into macrophages

  13. Inflammatory Response

  14. Complement System • A collection of plasma proteins • Activated when pathogens enter the body • Complements certain immune responses • Interferon binds to receptors of non-infected cells • Causes them to prepare for possible attack • Produce substances that interfere with viral replication

  15. Action of the Complement SystemAgainst a bacterium

  16. Specific Defenses • An antigen is any foreign substance that stimulates the immune system to react • Lymphocytes capable of recognizing antigens • Have antigen receptors on plasma membrane • Protein’s shape allow it to combine with a specific antigen

  17. Specific Defenses • Immunity primarily the result of • B lymphocytes • B cells give rise to plasma cells • Produce antibodies • T lymphocytes • T cells directly attack cells that bear non-self proteins

  18. Antibody-Mediated Immunity • Clonal selection theory: • The antigen selects which lymphocyte will • Undergo clonal expansion, and • Produce more lymphocytes • If the same antigen enters the system again • Memory B cells quickly divide • Give rise to more lymphocytes capable of quickly producing antibodies

  19. Clonal Selection Model as it Applies to B Cells

  20. Immunoglobins • IgG - Main antibody type in circulation • IgM - Found in circulation Largest antibody • IgA - Found in secretions • IgD - Found on surface of immature B cells • IgE - Found as antigen receptors on basophils in blood and on mast cells in tissue

  21. Structure of an Antibody

  22. T Cells • Requirements for T cell antigen recognition: • Antigen must be presented by an antigen-presenting cell • Antigen is first linked to a major histocompatibility complex (MHC) protein in the plasma membrane • Cytokines - signaling chemicals that stimulate various immune cells

  23. Clonal Selection Modelas it Applies to T cells

  24. Types of T Cells • Cytotoxic T Cells • Destroy antigen-bearing cells • Contain Perforins • Helper T Cells • Regulate immunity by secreting cytokines

  25. Cell-mediated Immunity

  26. Overview ofNonspecific and Specific Defenses

  27. Induced Immunity • Active Immunity • Immunization • Pathogens or pathogen products treated to remove virulence • Dependent upon memory B cells & memory T cells capable of responding to lower doses of antigen

  28. Active Immunity Due to Immunizations

  29. Passive Immunity • Passive immunity • Occurs when an individual is given prepared antibodies (immunoglobins) to combat a disease • Short-lived • Newborns are often passively immune due to mother’s blood

  30. Passive Immunity

  31. Cytokines and Immunity • Cytokines • Signaling molecules produced by lymphocytes, monocytes, or other cells • Both interferon and interleukins have been used as immunotherapeutic drugs • Enhance the ability of the individual’s T cells (and B cells) to fight cancer

  32. Production of Monoclonal Antibodies

  33. Immunity Side Effects • Allergies • Hypersensitivities to substances that ordinarily would not harm the body • Immediate Response • IgE antibodies • Delayed Response • Memory T cells

  34. Immunity Side Effects • Blood Type Reactions • ABO blood typing • Two self antigens - A and B • If same antigen and its antibody are present in the blood, agglutination occurs • Rh blood typing • People that are Rh+ have Rh factor • People that are Rh- do not have Rh factor • Rh- individuals may produce antibodies to Rh factor if exposed

  35. Blood Transfusions

  36. Hemolytic Disease of the Newborn

  37. Immunity Side Effects • Tissue Rejection • Antibodies and cytotoxic T cells bring about destruction of foreign tissues in the body • Immune system is correctly distinguishing between self and nonself • Autoimmune Diseases • Cytotoxic T cells or antibodies mistakenly attack the body’s own cells

  38. Review • The Lymphatic System • Lymph Vessels • Lymphoid Organs • Nonspecific Defenses • Barriers • Inflammatory Response • Specific Defenses • Antibodies • T Cells • Induced Immunity • Active versus Passive Immunity • Immunity Side Effects • Allergies • Blood Typing

  39. Lymph Transport & Immunity

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