Chapter 14-Lymphatic System and Immunity
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Chapter 14-Lymphatic System and Immunity

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Chapter 14-Lymphatic System and Immunity Chapter 14-Lymphatic System and Immunity Presentation Transcript

  • The Lymphatic System and Immunity Chapter 14 Pgs 427-455
  • Overview
    • Introduction
    • Organization of the Lymphatic System
      • Functions of the lymphatic system
      • Lymphatic vessels
      • Lymphocytes
      • Lymphoid nodules
      • Lymphoid organs
      • Lymphatic system and body defenses
    • Nonspecific Defenses
      • Physical barriers
      • Phagocytes
      • Immunological surveillance
      • Interferons
      • Complement
      • Inflammation
      • Fever
    • Specific Defenses: The Immune Response
      • Forms of immunity
      • Properties of immunity
      • Overview of immune response
      • T cells and cell-mediated immunity
      • B cells and antibody-mediated immunity
  • Introduction
    • Pathogens: microorganisms responsible for human diseases
      • Bacteria
      • Viruses
      • Fungi
      • Parasites
    • Lymphatic system
      • Keeps us alive and healthy
  • Organization of Lymphatic System
    • 3 components
      • Lymphatic vessels
      • Fluid (lymph)
      • Lymphoid organs
  • Functions of Lymphatic System
    • Production, maintenance, distribution of lymphocytes
      • Respond to presence of:
        • Invading pathogens
        • Abnormal body cells (virus-infected cells, cancer cells)
        • Foreign proteins (toxins released by bacteria)
    • Return of fluid and solutes from peripheral tissues to blood
    • Distribution of hormones, nutrients, and waste products from tissues of origin to general circulation
  • Lymphatic Vessels
  •  
  • Types of Lymphocytes
    • T cells (Thymus dependent)
      • 80% of circulating lymphocytes
      • Cytotoxic T cells
        • Directly attack foreign cells or body cells infected by viruses (cell-mediated immunity)
      • Helper T cells
        • Stimulate activities of both B and T cells
      • Suppressor T cells
        • Inhibit both T and B cells
  • Types of Lymphocytes
    • B cells (Bone-marrow derived)
      • 10-15% circulating lymphocytes
      • Plasma cells
        • Responsible for production and secretion of antibodies (immunoglobulins)
      • Responsible for antibody-mediated immunity
    • NK cells (Natural Killer)
      • 5-10%
      • Attack foreign cells, normal cells infected with viruses, and cancer cells
      • Immunological surveillance
  •  
  • Lymphoid Nodules
    • Masses of lymphoid tissue w/o a capsule
      • Increase and decrease size depending on # lymphocytes present
    • Found beneath epithelial lining of organs in:
      • Respiratory system
      • Digestive system
        • Tonsils
        • Peyer’s patches
      • Urinary system
  • Lymphoid Organs: Lymph Nodes
  • Lymphoid Organs: Thymus
  • Lymphoid Organs: Spleen
  • The Lymphatic System and Body Defenses
    • Nonspecific Defenses
      • Do not distinguish one threat from another
      • Physical barriers
      • Phagocytic cells
      • Immunological surveillance
      • Interferons
      • Complement
      • Inflammation
      • Fever
    • Specific Defenses
      • Protect against particular threats
      • Develop after birth
      • Dependent on activity of lymphocytes
      • B cells
      • T cells
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  • The Complement System
  •  
  • Macrophage
  • Specific Defense: The Immune Response
    • Respond to specific antigens
    • T cells
      • Cell-mediated immunity (cellular immunity)
      • Provide defense against abnormal cells and pathogens in living cells
    • B cells
      • Antibody-mediated immunity (humoral immunity)
      • Provide a defense against antigens and pathogens in body fluids
  • Immune System
  • Forms of Immunity
    • Either innate or acquired
    • Innate
      • Genetically determined
    • Acquired
      • Active or Passive
        • Active Immunity
          • Naturally acquired immunity
          • Induced active immunity
        • Passive Immunity
          • Induced passive immunity
          • Natural passive immunity
  •  
  • Properties of Immunity
    • Specificity
    • Versatility
    • Memory
    • Tolerance
  • Overview of Immune Response
  •  
  • T Cells and Cell-Mediated Immunity
    • T cells recognize antigens when bound to membranes of other cells
      • Membrane receptors called major histocompatibility complex (MHC) proteins
        • 2 classes
          • Class I MHC proteins
          • Class II MHC proteins
  • Class I MHC Proteins
    • Found on the surfaces of all of our cells
    • MHC proteins bind small peptide molecules normally present on cell membrane
      • Normal peptides: T cell ignores
      • Abnormal, virus, or bacteria (nonself): T cell activated
        • Destroys abnormal/infected cell
  • Class II MHC Proteins
    • Found only on membranes of lymphocytes and phagocytic antigen-presenting cells (APCs)
      • Such as monocyte-macrophage group, free and fixed macrophages
      • Specialized for activating T cells against foreign cells and proteins
    • Phagocytic APCs engulf and break down foreign antigens or pathogens
      • Fragments of foreign antigens displayed on phagocytic cell’s membrane
        • Bind to Class II MHC proteins
        • T cells come in contact and become activated, starting the immune response
  •  
  • T Cells
    • T cell activation for both occur when MHC protein contains specific antigen T cell programmed to detect
      • Once activated, T cells divide and differentiate in to cells with specific function in immune response
        • Cytotoxic T cells
        • Helper T cells
        • Memory T cells
        • Suppressor T cells
  • Cytotoxic T Cells
    • Responsible for cell-mediated immunity
    • Activated by exposure to antigens bound to Class I MHC proteins
      • Activated cells under cell division that produce active cytotoxic T cells and memory cells
    • Track down and attack bacteria, fungi, protozoa, or foreign transplanted tissue
  • Cytotoxic T Cells
    • Destruction occurs by:
      • Releasing perforin (destructive protein)
        • Ruptures antigenic cell membrane
      • Secreting lymphotoxin (poison)
        • Kills target cell
      • Apoptosis
        • Genetically programmed cell death
        • T cells activate the genes within the target cell
    • Also called Killer T cells
  •  
  •  
  • Apoptosis and Macrophages
  • Helper T Cells
    • Activated by exposure to antigens bound to Class II MHC proteins
    • Activated  divide to produce
      • Active Helper T cells and memory cells
    • Release variety of cytokines that:
      • Coordinate specific and nonspecific defenses
      • Stimulate cell mediated and antibody-mediated immunity
  • Memory T Cells
    • During cell division for both cytotoxic and helper T cells, some develop into memory cells
    • Remain in reserve
    • If same antigen attacks 2 nd time, memory T cells immediately differentiate into cytotoxic T cells and helper T cells
      • Allows for more rapid and effective immune response
  • Suppressor T Cells
    • When activated, depress responses of other T and B cells
    • Does not occur immediately
      • Takes much longer for these cells to become activated
      • Act after initial immune response
  • B Cells and Antibody-Mediated Immunity: B Cell Activation
    • Each B cell carries its antibody molecules in its cell membrane
      • If ISF contains antigens that can bind to antibodies, B cells become sensitized
        • Antigens enter B cell and become displayed on Class II MHC proteins on surface of B cell
          • Helper T cell activated by same antigen attaches to MHC protein-antigen complex and secretes cytokines that:
            • Promote B cell activation
            • Stimulate B cell division
            • Accelerate plasma cell production
            • Enhance antibody production
  • B Cell Activation
    • Activated B cells divide several times
      • Produce daughter cells that differentiate into:
        • Plasma cells
          • Synthesize and secrete large numbers of antibodies on surface of sensitized B cells
        • Memory cells
          • Similar to memory T cells
          • If exposed to same antigen, will differentiate into plasma cells
  •  
  •  
  •  
  • Antibody Structure
    • Consist of short and heavy chains of polypeptides
      • Each chain has constant and variable segments
        • Constant heavy chains form base of antibody molecule
          • B cells produce only 5 types of constant segments
      • Specificity depends on variable segments of light and heavy chains
        • Free tips contain antigen binding sites (very specific for each type of antigen)
    • Antigen-antibody complex
      • Forms when antibody binds to proper antigen
      • Binds to sites and leads to B cell sensitization and an immune response
  •  
  •  
  • Classes of Antibodies (Immunoglobins Igs)
    • IgG
      • Largest and most diverse
      • Resist many viruses, bacteria, bacterial toxins
      • Can cross placenta
        • What type of immunity is that?
    • IgM
      • Circulate; attack bacteria
    • IgA
      • Found in exocrine secretions
        • Ex?
      • Attack pathogens before they enter the body
    • IgE
      • When bound to antigen, stimulates basophils and mast cells to release chemicals to stimulate inflammation
    • IgD
      • Attached to B cell and involved in their activation
  • Antibody Function
    • Neutralization
    • Agglutination and Precipitation
    • Activation of a complement
    • Attraction of phagocytes
    • Enhancement of phagocytosis
    • Stimulation of inflammation
  • Primary and Secondary Responses to Antigen Exposure
  • Cool Links!
    • Fun immune game
      • http://nobelprize.org/medicine/educational/immunity/index.html
    • Cool Cytotoxic T cells
      • http://www.cellsalive.com/ctl.htm
    • Copy and paste them into your browser