Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
LYMPHATIC SYSTEM Aka… the immune system Lymphatic System Definitions • Pathogens—Organisms that cause disease • Lymphatic System—Cells, tissues, and organs that play a central role in the body’s defenses against pathogens • Lymphatic system consists of vessels (lymphatics) filled with lymph connected to lymphatic organs Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization The Components of the Lymphatic System Figure 14-1 Functions of the Lymphatic System • Produce, maintain, distribute lymphocytes • Lymphocytes attack invading organisms, abnormal cells, foreign proteins • Maintain blood volume • Help eliminate local variations in interstitial fluid concentration Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization Lymphatic Capillaries Figure 14-2(a) Lymphatic System Organization Lymphatic Capillaries Figure 14-2(b) Lymphatic System Organization The Lymphatic Ducts and the Venous System Figure 14-3 Cells involved in immunity Three Classes of Lymphocytes • T cells • Thymus dependent • B cells • Bone marrow derived • NK cells • Natural killer Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Types of T Lymphocytes • Cytotoxic T cells • Provide cell-mediated immunity • Attack foreign and virus-infected cells • Regulatory T cells • Helper T cells • Suppressor T cells • Memory cells Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings B Lymphocytes • Can become plasma cells • Specific to a particular antigen • Produce antibodies that react with that antigen • Antibodies are immunoglobulins • Responsible for humoral or antibody-mediated immunity Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings NK Lymphocytes • Provide immunological surveillance • Attack cells • Foreign cells • Virally-infected cells • Cancerous cells Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphocyte Life Cycle • Continuously migrate between lymphoid tissues and the blood • Production and development (called lymphopoiesis) involves: • Bone marrow • Thymus • Peripheral lymphoid tissues Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization The Origins of Lymphocytes Figure 14-4 Lymphoid Nodules • Consists of loose connective tissue containing densely packed lymphocytes • Tonsils are lymphoid nodules in the pharynx wall Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization The Tonsils Figure 14-5 Lymphoid Organs • Important lymphoid organs include: • Lymph nodes • Thymus • Spleen • Located in areas that are vulnerable to pathogens Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes • Encapsulated masses of lymphoid tissue containing lymphocytes • Monitor and filter lymph • Remove antigens • Initiate immune response Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization The Structure of a Lymph Node Figure 14-6 The Thymus • Lies behind sternum • T cells divide and mature there • Shrinks after puberty • Produces thymosins • Hormones that regulate T cell development Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization The Thymus Figure 14-7 Lymphatic System Organization The Thymus Figure 14-7(a) Lymphatic System Organization The Thymus Figure 14-7(b) Lymphatic System Organization The Thymus Figure 14-7(c) The Spleen • White pulp • Resembles lymphoid nodules • Removes antigens • Initiates immune response • Red pulp • Contains red blood cells • Recycles damaged or out-dated RBCs • Stores iron from recycled RBCs Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic System Organization The Spleen Figure 14-8 Lymphatic System Organization The Spleen Figure 14-8(a) Lymphatic System Organization The Spleen Figure 14-8(b) Overview of Body’s Defenses • Non-specific defenses • Protect against any threat • Specific defenses • Protect against particular threats • Responds to antigens Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Nonspecific Defenses: 1 • Physical Barriers • Skin, hair, & skin secretions • Digestive epithelia, & secretions Figure 14-9 (1 of 7) Nonspecific Defenses:2 • Phagocytes • Microphages (neutrophils, eosinophils) • Macrophages Figure 14-9 (2 of 7) Nonspecific Defenses:3 • Immunological Surveillance • NK cells • Find, kill cancer and virus-infected cells Figure 14-9 (3 of 7) Nonspecific Defenses:4 • Inflammatory Response • Coordinated non-specific response to tissue injury Figure 14-9 (6 of 7) Nonspecific Defenses:5 • Fever • Temperature greater than 99ºF • Inhibits pathogens • Accelerates metabolism Figure 14-9 (7 of 7) Specific Defenses: Immunity: Roles for Activated T Cells • Cytotoxic (killer) T cells • Provide cell-mediated immunity • Memory T cells • Remember the activating antigen • Suppressor T cells • Suppress other T and B cells • Helper T cells • Secrete regulatory cytokines Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Specific Defenses: Immunity: B Cells and Antibody-Mediated Immunity • B cells are first sensitized by exposure to “their” antigen • Helper T cells for that antigen then activate those B cells • Activated B cells divide to form: • Plasma cells • Produce antibodies against that antigen • Memory cells Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Specific Defenses: Immunity Antibody Structure Figure 14-15 Properties of Specific Immunity • Specificity • T and B cell membrane receptors recognize a unique antigen • Versatility • Responsive to millions of antigens • Memory • Memory cells recall earlier encounters with an antigen • Tolerance • Ignores body’s own antigens Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Specific Defenses: Immunity Types of Immunity • Innate immunity • Genetically determined • Present at birth • Acquired immunity • Active • Follows exposure to antigen • Passive • From transfer of antibodies from outside source Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Specific Defenses: Immunity Types of Immunity Figure 14-11 Overview of the Immune Response • Purpose is to inactivate or destroy: • Pathogens • Abnormal cells • Foreign molecules • Based on activation of lymphocytes by specific antigens by antigen recognition Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Direct physical and chemical attack CELL–MEDIATED IMMUNITY ANTIGENS Bacteria SPECIFIC DEFENSES (Immune response) Phagocytes activated T cells activated Communication and feedback ANTIBODY–MEDIATED IMMUNITY Viruses B cells activated Attack by circulating antibodies Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14-12 1 of 7 ACTIVATION AND CELL DIVISION Infected cell Viral or bacterial antigen Inactive cytotoxic T cell Memory T cells (inactive) Class I MHC protein T cell receptor Active cytotoxic T cells Lymphotoxin release Disruption of cell metabolism Cytokine release Perforin release Destruction of cell membrane Stimulation of apoptosis Figure 14-13 1 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Lysed cell DESTRUCTION OF TARGET CELL Sensitization Antigens Activation Class II MHC Inactive B cell T cell receptor Antigen Class II MHC Antibodies Division and differentiation B cell ANTIBODY PRODUCTION T cell Antigens bound to antibody molecules Stimulation by cytokines Plasma cells Antigen binding Sensitized B cell Helper T cell Activated B cells Sensitized B cell Memory B cells (inactive) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14-14 1 of 5 Primary and Secondary Immune Response • Primary response—Antibodies produced by plasma cells after first exposure to antigen • Secondary response—Maximum antibody levels produced by subsequent exposure to the same antibody Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Specific Defenses: Immunity The Primary and Secondary Immune Responses Figure 14-16 Specific Defenses: Immunity Key Note Immunization produces a primary response to a specific antigen. If the same antigen is encountered at a later date, it triggers a powerful secondary response that usually prevents infection and disease. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Immune Disorders • Autoimmune disorders • Mistaken attack on body’s own tissues • Immunodeficiency disease • Disease (e.g., AIDS) or a congenital block of immunity • Allergies • Inappropriate or excessive response to allergens • Age-related loss of effectiveness Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings