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Transcript
Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Chapter 22 Lecture Outline* *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. 22-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 22 Lymphatic System and Immunity 22-2 Lymphatic System • • • • • • • • Lymph Lymphatic vessels Lymphatic tissue Lymphatic nodules Lymph nodes Tonsils Spleen Thymus 22-3 Functions of the Lymphatic System • Fluid balance – Excess interstitial fluid enters lymphatic capillaries and becomes lymph • Fat absorption – Absorption of fat and other substances from digestive tract • Defense – Microorganisms and other foreign substances are filtered from lymph by lymph nodes and from blood by spleen 22-4 Lymphatic Vessels • Carry lymph away from tissues • Lymphatic capillaries – More permeable than blood capillaries – Epithelium functions as series of one-way valves 22-5 Lymphatic Vessels • Lymphatic capillaries join to form • Lymphatic vessels – Have valves that ensure one-way flow • Lymph nodes: Distributed along vessels and filter lymph • Lymphatic trunks: Jugular, subclavian, bronchomediastinal, intestinal, lumbar • Lymphatic ducts: Right and thoracic which connect to large veins 22-6 Lymph Drainage Into Veins 22-7 Lymphatic Tissue and Nodules • Lymphatic tissue – Consists mainly of lymphocytes – Encapsulated or not • Lymphatic nodules – Numerous in loose connective tissue of digestive (Peyer’s patches), respiratory, urinary, reproductive systems 22-8 Tonsils • Large groups of lymphatic nodules in nasopharynx and oral cavity • Provide protection against bacteria and other harmful material • Groups – Palatine – Pharyngeal – Lingual 22-9 Lymph Nodes • Organized in cortex and medulla • Substances removed by phagocytosis or stimulate lymphocytes or both • Only structures to filter lymph – Afferent and efferent vessels 22-10 Spleen • Located in left superior side of abdomen – Can be ruptured in traumatic abdominal injuries resulting in bleeding, shock, death • Blood flows through at 3 different rates – Fast (most), slow, intermediate • Functions – Destroys defective RBCs – Detects and responds to foreign substances – Limited reservoir for blood 22-11 Spleen 22-12 Thymus • Located in superior mediastinum • Divisions: Cortex and medulla • Site of maturation of T cells 22-13 Immunity • Ability to resist damage from foreign substances as microorganisms and harmful chemicals • Categories – Innate or nonspecific resistance • Mechanical mechanisms: Prevent entry or remove microbes • Chemical mediators: Promote phagocytosis and inflammation • Cells: Involved in phagocytosis and production of chemicals – Adaptive or specific immunity • Specificity: Ability to recognize a particular substance • Memory: Ability to remember previous encounters with a particular substance and respond rapidly 22-14 Mechanical Mechanisms and Chemical Mediators • Mechanical Mechanisms – Skin, tears, saliva, mucous membranes, mucus • Chemical Mediators – Complement • Group of 20 proteins • Circulate in blood in inactive form • Become activated in cascade form: Classical or alternative pathway – Interferons • Prevent viral replication 22-15 Complement Cascade 22-16 Innate Immunity: Cells • White blood cells – Most important cellular components of immune system – Methods • Chemotaxis • Phagocytosis • Neutrophils – Phagocytic and first cells to enter infected tissue • Macrophages – Monocytes that leave blood, enter tissues – Large phagocytic cells • Basophils and mast cells – Promote inflammation • Eosinophils – Reduce inflammation • Natural killer cells – Lyse tumor and virusinfected cells 22-17 Inflammatory Response 22-18 Inflammatory Response • Tissue injury regardless of type can cause inflammation • Response initiated by chemical mediators that produce vasodilation, chemotactic attraction, increased vascular permeability • Types – Local: Symptoms are redness, heat, swelling, pain, loss of function – Systemic: Symptoms are increase in neutrophil numbers, fever and shock 22-19 Adaptive Immunity • Involves the ability to recognize, respond to, and remember a particular substance • Stimulants – Antigens: Large molecules • Foreign: Not produced by body, introduced from outside • Self-antigens: Produced by body – Haptens: Small molecules and capable of combining • Types – Humoral or Antibody-mediated: B cells – Cell-mediated: T cells 22-20 Origin and Development of Lymphocytes • B and T cells – Originate in red bone marrow – Move to lymphatic tissue from processing sites and continually circulate – Clones are small groups of identical lymphocytes 22-21 Origin and Development of Lymphocytes • Positive selection – Ensures survival of lymphocytes that react against antigens • Negative selection – Eliminates lymphocytes that react against self-antigens • Primary lymphatic organs (red bone marrow, thymus) – Where lymphocytes mature into functional cells • Secondary lymphatic organs – Where lymphocytes produce an immune response 22-22 Antigenic Determinants • Antigenic determinants – Specific regions of a given antigen recognized by a lymphocyte • Antigenic receptors – Surface of lymphocyte that combines with antigenic determinant 22-23 Major Histocompatability Complex (MHC) • Most lymphocyte activation involves glycoproteins of cell surfaces called MHC molecules – Class I molecules display antigens on surface of nucleated cells, resulting in destruction of cells – Class II molecules display antigens on surface of antigen-presenting cells, resulting in activation of immune cells 22-24 Antigen Processing 22-25 Costimulation 22-26 Proliferation of Helper T Cells 22-27 Proliferation of B Cells 22-28 Lymphocyte Inhibition • Tolerance: To prevent the immune system from responding to self-antigens – Provoked by • Deletion of self-reactive lymphocytes • Preventing activation of lymphocytes • Activation of suppressor T cells 22-29 Antibody-Mediated Immunity • Antibodies or Immunoglobulins (Ig) – Classes: IgG, IgM, IgA, IgE, IgD – Structure • Variable region: Part that combines with anitgenic determinant of antigen • Constant region: Responsible for activities 22-30 Actions of Antibodies 22-31 Antibody Production 22-32 Cell-Mediated Immunity • Antigen activates effector T cells and produces memory T cells • Cytotoxic T cells lyse virus-infected cells, tumor cells, and tissue transplants • Cytotoxic T cells produce cytokines, which promote phagocytosis and inflammation 22-33 Interactions and Responses of Innate and Adaptive Immunity 22-34 Acquired Immunity • Active natural immunity – Results from natural exposure to an antigen • Active artificial immunity – Results from deliberate exposure to an antigen • Passive natural immunity – Results from transfer of antibodies from a mother to her fetus or baby • Passive artificial immunity – Results from transfer of antibodies (or cells) from an immune animal to a nonimmune one 22-35 Ways to Acquire Adaptive Immunity 22-36 Effects of Aging • Little effect on lymphatic system • Decreased ability of helper T cells to proliferate in response to antigens • Decreased primary and secondary antibody responses • Decreased ability of cell-mediated immunity to resist intracellular pathogens 22-37 Immune System Problems • Hypersensitivity reactions • Autoimmune disease • Severe combined immunodeficiency disease (SCID) • Transplantation – Acute rejection – Chronic rejection 22-38