BIO 094 Power Point Chapter 12

The Lymphatic System and Body Defenses : The Lymphatic System and Body Defenses

The Lymphatic System : The Lymphatic System Consists of two semi-independent parts Lymphatic vessels Lymphoid tissues and organs Lymphatic system functions Transports escaped fluids back to the blood Plays essential roles in body defense and resistance to disease

Lymphatic Characteristics : Lymphatic Characteristics Lymph—excess tissue fluid carried by lymphatic vessels Properties of lymphatic vessels One way system toward the heart No pump Lymph moves toward the heart Milking action of skeletal muscle Rhythmic contraction of smooth muscle in vessel walls

Relationship of Lymphatic Vessels to Blood Vessels : Relationship of Lymphatic Vessels to Blood Vessels Figure 12.1

Lymphatic Vessels : Lymphatic Vessels Lymph capillaries Walls overlap to form flap-like minivalves Fluid leaks into lymph capillaries Capillaries are anchored to connective tissue by filaments Higher pressure on the inside closes minivalves Fluid is forced along the vessel

Lymphatic Vessels : Lymphatic Vessels Figure 12.2a

Lymphatic Vessels : Lymphatic Vessels Figure 12.2b

Lymphatic Vessels : Lymphatic Vessels Lymphatic collecting vessels Collect lymph from lymph capillaries Carry lymph to and away from lymph nodes Return fluid to circulatory veins near the heart Right lymphatic duct Thoracic duct

Lymphatic Vessels : Figure 12.3 Lymphatic Vessels

Lymph : Lymph Harmful materials that enter lymph vessels Bacteria Viruses Cancer cells Cell debris

Lymph Nodes : Lymph Nodes Filter lymph before it is returned to the blood Defense cells within lymph nodes Macrophages—engulf and destroy foreign substances Lymphocytes—provide immune response to antigens

Lymph Nodes : Lymph Nodes Figure 12.3

Lymph Node Structure : Lymph Node Structure Most are kidney-shaped and less than 1 inch long Cortex Outer part Contains follicles—collections of lymphocytes Medulla Inner part Contains phagocytic macrophages

Lymph Node Structure : Figure 12.4 Lymph Node Structure

Flow of Lymph Through Nodes : Flow of Lymph Through Nodes Lymph enters the convex side through afferent lymphatic vessels Lymph flows through a number of sinuses inside the node Lymph exits through efferent lymphatic vessels Fewer efferent than afferent vessels causes flow to be slowed

Other Lymphoid Organs : Other Lymphoid Organs Several other organs contribute to lymphatic function Spleen Thymus Tonsils Peyer’s patches

Other Lymphoid Organs : Other Lymphoid Organs Figure 12.5

Other Lymphatic Tissues : Other Lymphatic Tissues Spleen Located on the left side of the abdomen Filters blood Destroys worn out blood cells Forms blood cells in the fetus Acts as a blood reservoir Thymus Gland Located low in the throat, overlying the heart Functions at peak levels only during childhood Produces hormones (like thymosin) to program lymphocytes

Other Lymphatic Tissues : Other Lymphatic Tissues Tonsils Small masses of lymphoid tissue around the pharynx Trap and remove bacteria and other foreign materials Tonsillitis is caused by congestion with bacteria Peyer’s Patches Found in the wall of the small intestine Resemble tonsils in structure Capture and destroy bacteria in the intestine

Mucosa-Associated Lymphatic Tissue (MALT) : Mucosa-Associated Lymphatic Tissue (MALT) Includes Peyer’s patches Tonsils Other small accumulations of lymphoid tissue Acts as a sentinel to protect respiratory and digestive tracts

Body Defenses : Body Defenses The body is constantly in contact with bacteria, fungi, and viruses The body has two defense systems for foreign materials Innate (nonspecific) defense system Adaptive (specific) defense system Immunity—specific resistance to disease

Immune System : Immune System Figure 12.6

Body Defenses : Body Defenses Innate defense system (nonspecific defense system) Mechanisms protect against a variety of invaders Responds immediately to protect body from foreign materials Adaptive defense system (specific defense system) Specific defense is required for each type of invader

Innate Body Defenses : Innate Body Defenses Innate body defenses are mechanical barriers to pathogens such as Body surface coverings Intact skin Mucous membranes Specialized human cells Chemicals produced by the body

Innate Body Defenses : Innate Body Defenses Table 12.1 (1 of 2)

Surface Membrane Barriers:First Line of Defense : Surface Membrane Barriers:First Line of Defense Skin and mucous membranes Physical barrier to foreign materials Also provide protective secretions pH of the skin is acidic to inhibit bacterial growth Sebum is toxic to bacteria Vaginal secretions are very acidic

Surface Membrane Barriers:First Line of Defense : Surface Membrane Barriers:First Line of Defense Stomach mucosa Secretes hydrochloric acid Has protein-digesting enzymes Saliva and lacrimal fluid contain lysozymes, an enzyme that destroy bacteria Mucus traps microogranisms in digestive and respiratory pathways

Cells and Chemicals:Second Line of Defense : Cells and Chemicals:Second Line of Defense Phagocytes Natural killer cells Inflammatory response Antimicrobial proteins Fever

Cells and Chemicals:Second Line of Defense : Cells and Chemicals:Second Line of Defense Phagocytes Cells such as neutrophils and macrophages Engulf foreign material into a vacuole Enzymes from lysosomes digest the material

Phagocytes : Phagocytes Figure 12.7a

Slide 31 : Figure 12.7b Lysosome Microbe adheres to phagocyte Phagocyte engulfs the particle Phagocytic vesicle isfused with a lysosome Microbe in fused vesicleis killed and digested bylysosomal enzymes withinthe phagolysosome Indigestible andresidual materialis removed byexocytosis Phagocytic vesiclecontaining microbeantigen (phagosome) Phagolysosome Lysosomalenzymes (b)

Internal Innate Defenses: Cells and Chemicals : Internal Innate Defenses: Cells and Chemicals Natural killer (NK) cells Can lyse (disintegrate or dissolve) and kill cancer cells Can destroy virus-infected cells

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Inflammatory response Triggered when body tissues are injured Four most common indicators of acute inflammation Redness Heat Swelling Pain Results in a chain of events leading to protection and healing

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Functions of the inflammatory response Prevents spread of damaging agents Disposes of cell debris and pathogens through phagocytosis Sets the stage for repair

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Antimicrobial proteins Attack microorganisms Hinder reproduction of microorganisms Most important Complement proteins Interferon

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Complement proteins A group of at least 20 plasma proteins Activated when they encounter and attach to cells (complement fixation) Damage foreign cell surfaces Release vasodilators and chemotaxis chemicals, cause open pores in the cell – destroy!

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Figure 12.10

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Interferon Proteins secreted by virus-infected cells Bind to healthy cell surfaces to interfere with the ability of viruses to multiply

Cells and Chemicals: Second Line of Defense : Cells and Chemicals: Second Line of Defense Fever Abnormally high body temperature Hypothalamus heat regulation can be reset by pyrogens (secreted by white blood cells) High temperatures inhibit the release of iron and zinc from the liver and spleen needed by bacteria Fever also increases the speed of tissue repair

Summary of Nonspecific Body Defenses : Summary of Nonspecific Body Defenses Table 12.1 (2 of 2)

Adaptive Defense System: Third Line of Defense : Adaptive Defense System: Third Line of Defense Three aspects of adaptive defense Antigen specific—recognizes and acts against particular foreign substances Systemic—not restricted to the initial infection site Memory—recognizes and mounts a stronger attack on previously encountered pathogens

Adaptive Defense System: Third Line of Defense : Adaptive Defense System: Third Line of Defense Types of Immunity Humoral immunity = antibody-mediated immunity Provided by antibodies present in body fluids Cellular immunity = cell-mediated immunity Targets virus-infected cells, cancer cells, and cells of foreign grafts

Adaptive Defense System: Third Line of Defense : Adaptive Defense System: Third Line of Defense Antigens (nonself) Any substance capable of exciting the immune system and provoking an immune response Examples of common antigens Foreign proteins (strongest) Nucleic acids Large carbohydrates Some lipids Pollen grains Microorganisms

Adaptive Defense System: Third Line of Defense : Adaptive Defense System: Third Line of Defense Cells of the adaptive defense system Lymphocytes respond to specific antigens B lymphocytes (B cells) T lymphocytes (T cells) Macrophages help lymphocytes

Adaptive Defense System: Third Line of Defense : Adaptive Defense System: Third Line of Defense Immunocompetent—cell becomes capable of responding to a specific antigen by binding to it Cells of the adaptive defense system Lymphocytes Originate from hemocytoblasts in the red bone marrow B lymphocytes become immunocompetent in the bone marrow (remember B for Bone marrow) T lymphocytes become immunocompetent in the thymus (remember T for Thymus)

Lymphocyte Differentiation and Activation : Lymphocyte Differentiation and Activation Figure 12.11

Adaptive Defense System: Third Line of Defense : Adaptive Defense System: Third Line of Defense Cells of the adaptive defense system (continued) Macrophages Arise from monocytes Become widely distributed in lymphoid organs Secrete cytokines (proteins important in the immune response) Tend to remain fixed in the lymphoid organs

Humoral (Antibody-Mediated) Immune Response : Humoral (Antibody-Mediated) Immune Response B lymphocytes with specific receptors bind to a specific antigen The binding event activates the lymphocyte to undergo clonal selection A large number of clones are produced (primary humoral response) Most B cells become plasma cells Produce antibodies to destroy antigens Activity lasts for 4 or 5 days Some B cells become long-lived memory cells (secondary humoral response)

Humoral Immune Response : Humoral Immune Response Secondary humoral responses Memory cells are long-lived A second exposure causes a rapid response The secondary response is stronger and longer lasting

Humoral Immune Response : Figure 12.12 Humoral Immune Response

Humoral Immune Response : Figure 12.13 Humoral Immune Response

Active Immunity : Active Immunity Occurs when B cells encounter antigens and produce antibodies Active immunity can be Naturally acquired during bacterial and viral infections Artificially acquired from vaccines

Passive Immunity : Passive Immunity Occurs when antibodies are obtained from someone else Conferred naturally from a mother to her fetus (naturally acquired) Conferred artificially from immune serum or gamma globulin (artificially acquired) Immunological memory does not occur Protection provided by “borrowed antibodies”

Passive Immunity : Passive Immunity Monoclonal antibodies Antibodies prepared for clinical testing or diagnostic services Produced from descendents of a single cell line Examples of uses for monoclonal antibodies Diagnosis of pregnancy Treatment after exposure to hepatitis and rabies

Types of Acquired Immunity : Types of Acquired Immunity Figure 12.14

Antibodies (Immunoglobulins or Igs) : Antibodies (Immunoglobulins or Igs) Soluble proteins secreted by B cells (plasma cells) Carried in blood plasma Capable of binding specifically to an antigen

Antibodies : Antibodies Antibody classes Antibodies of each class have slightly different roles Five major immunoglobulin classes (MADGE) IgM—can fix complement IgA—found mainly in mucus IgD—important in activation of B cell IgG—can cross the placental barrier and fix complement IgE—involved in allergies

Antibodies : Antibodies Antibody function Antibodies inactivate antigens in a number of ways Complement fixation Neutralization Agglutination Precipitation

Antibody Function : Antibody Function Figure 12.16

Cellular (Cell-Mediated) Immune Response : Cellular (Cell-Mediated) Immune Response Antigens must be presented by macrophages to an immunocompetent T cell (antigen presentation) T cells must recognize nonself and self (double recognition) After antigen binding, clones form as with B cells, but different classes of cells are produced

Cellular (Cell-Mediated) Immune Response : Cellular (Cell-Mediated) Immune Response Figure 12.17

Cellular (Cell-Mediated) Immune Response : Cellular (Cell-Mediated) Immune Response T cell clones Cytotoxic (killer) T cells Specialize in killing infected cells Insert a toxic chemical (perforin) Helper T cells Recruit other cells to fight the invaders Interact directly with B cells

Cellular (Cell-Mediated) Immune Response : Cellular (Cell-Mediated) Immune Response Figure 12.18

Functions of Cells and Molecules Involved in Immunity : Functions of Cells and Molecules Involved in Immunity Table 12.3 (1 of 2)

Functions of Cells and Molecules Involved in Immunity : Functions of Cells and Molecules Involved in Immunity Table 12.3 (2 of 2)

Summary of Adaptive Immune Response : Figure 12.19 Summary of Adaptive Immune Response

Disorders of Immunity: Allergies (Hypersensitivity) : Disorders of Immunity: Allergies (Hypersensitivity) Abnormal, vigorous immune responses Types of allergies Immediate hypersensitivity Triggered by release of histamine from IgE binding to mast cells Reactions begin within seconds of contact with allergen Anaphylactic shock—dangerous, systemic response

Disorders of Immunity: Allergies (Hypersensitivity) : Disorders of Immunity: Allergies (Hypersensitivity) Types of allergies (continued) Delayed hypersensitivity Triggered by the release of lymphokines from activated helper T cells Symptoms usually appear 1–3 days after contact with antigen

Allergy Mechanisms : Allergy Mechanisms Figure 12.20, step 3

Allergy Mechanisms : Allergy Mechanisms Figure 12.20, step 6

Allergy Mechanisms : Allergy Mechanisms Figure 12.20, step 7

Disorders of Immunity: Immunodeficiencies : Disorders of Immunity: Immunodeficiencies Production or function of immune cells or complement is abnormal May be congenital or acquired Includes AIDS (Acquired Immune Deficiency Syndrome)

Autoimmune Diseases - Self Tolerance Breakdown : Autoimmune Diseases - Self Tolerance Breakdown Inefficient lymphocyte programming Appearance of self-proteins in the circulation that have not been exposed to the immune system Eggs / Sperm Proteins in the thyroid gland Cross-reaction of antibodies produced against foreign antigens with self-antigens Rheumatic fever

Disorders of Immunity: Autoimmune Diseases : Disorders of Immunity: Autoimmune Diseases The immune system does not distinguish between self and nonself The body produces antibodies and sensitized T lymphocytes that attack its own tissues

Disorders of Immunity: Autoimmune Diseases : Disorders of Immunity: Autoimmune Diseases Examples of autoimmune diseases Multiple sclerosis—white matter of brain and spinal cord are destroyed Type I diabetes mellitus—destroys pancreatic beta cells that produce insulin Rheumatoid arthritis—destroys joints Glomerulonephritis—impairment of renal function

Developmental Aspects of the Lymphatic System and Body Defenses : Developmental Aspects of the Lymphatic System and Body Defenses Except for thymus and spleen, the lymphoid organs are poorly developed before birth A newborn has no functioning lymphocytes at birth, only passive immunity from the mother If lymphatics are removed or lost, severe edema results, but vessels grow back in time