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. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Lymphatic System and Immunity Chapter 22 Lymphatic System and Immunity

Lymphatic System Lymph Lymphatic vessels Lymphatic tissue Lymphatic nodules Lymph nodes Tonsils Spleen Thymus

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

Lymphatic Vessels Carry lymph away from tissues Lymphatic capillaries More permeable than blood capillaries Epithelium functions as series of one-way valves

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

Lymph Drainage Into Veins

Lymphatic Tissue and Nodules Consists mainly of lymphocytes Encapsulated or not Lymphatic nodules Numerous in loose connective tissue of digestive (Peyer’s patches), respiratory, urinary, reproductive systems

Tonsils Large groups of lymphatic nodules in nasopharynx and oral cavity Provide protection against bacteria and other harmful material Groups Palatine Pharyngeal Lingual

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

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

Spleen

Thymus Located in superior mediastinum Divisions: Cortex and medulla Site of maturation of T cells

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

Mechanical Mechanisms and 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 Mechanical Mechanisms Skin, tears, saliva, mucous membranes, mucus

Complement Cascade

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 virus-infected cells

Inflammatory Response

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

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

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

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

Antigenic Determinants Specific regions of a given antigen recognized by a lymphocyte Antigenic receptors Surface of lymphocyte that combines with antigenic determinant

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

Antigen Processing

Costimulation

Proliferation of Helper T Cells

Proliferation of B Cells

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

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

Actions of Antibodies

Antibody Production

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

Interactions and Responses of Innate and Adaptive Immunity

Acquired Immunity Active natural immunity Active artificial 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

Ways to Acquire Adaptive Immunity

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

Immune System Problems Hypersensitivity reactions Autoimmune disease Severe combined immunodeficiency disease (SCID) Transplantation Acute rejection Chronic rejection