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© 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 1 of 2) Innate Defenses Physical barriers keep hazardous organisms and materials outside.

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Presentation on theme: "© 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 1 of 2) Innate Defenses Physical barriers keep hazardous organisms and materials outside."— Presentation transcript:

1 © 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 1 of 2) Innate Defenses Physical barriers keep hazardous organisms and materials outside the body. Phagocytes engulf pathogens and cell debris. Immunological surveillance is the destruction of abnormal cells by NK cells in peripheral tissues. Interferons are chemical messengers that coordinate the defenses against viral infections. Duct of eccrine sweat gland Hair Fixed macrophage Neutrophil Free macrophage Natural killer cell Lysed abnormal cell Eosinophil Monocyte Secretions Epithelium Interferons released by activated lymphocytes, macrophages, or virus-infected cells p. 779

2 © 2012 Pearson Education, Inc. Figure 22-12 How Natural Killer Cells Kill Cellular Targets (Step 1) Recognition and Adhesion NK cell Golgi apparatus Abnormal cell p. 781

3 © 2012 Pearson Education, Inc. Figure 22-12 How Natural Killer Cells Kill Cellular Targets (Step 2) Realignment of Golgi apparatus p. 781

4 © 2012 Pearson Education, Inc. Figure 22-12 How Natural Killer Cells Kill Cellular Targets (Step 3) Secretion of Perforin Perforin molecules NK cell Abnormal cell Pores formed by perforin complex p. 781

5 © 2012 Pearson Education, Inc. Figure 22-12 How Natural Killer Cells Kill Cellular Targets (Step 4) Lysis of Abnormal Cell p. 781

6 © 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 1 of 2) Innate Defenses Physical barriers keep hazardous organisms and materials outside the body. Phagocytes engulf pathogens and cell debris. Immunological surveillance is the destruction of abnormal cells by NK cells in peripheral tissues. Interferons are chemical messengers that coordinate the defenses against viral infections. Duct of eccrine sweat gland Hair Fixed macrophage Neutrophil Free macrophage Natural killer cell Lysed abnormal cell Eosinophil Monocyte Secretions Epithelium Interferons released by activated lymphocytes, macrophages, or virus-infected cells p. 779

7 © 2012 Pearson Education, Inc. Figure 22-13 Interferons Alpha (  )-interferons are produced by cells infected with viruses. They attract and stimulate NK cells and enhance resistance to viral infection. Beta (  )-interferons, secreted by fibroblasts, slow inflammation in a damaged area. Gamma (  )-interferons, secreted by T cells and NK cells, stimulate macrophage activity. p. 782

8 © 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 2 of 2) Complement system consists of circulating proteins that assist antibodies in the destruction of pathogens. is a localized, tissue-level response that tends to limit the spread of an injury or infection. Inflammatory response is an elevation of body temperature that accelerates tissue metabolism and the activity of defenses. Fever Mast cell Complement Lysed pathogen Body temperature rises above 37.2ºC in response to pyrogens 1. Blood flow increased 2. Phagocytes activated 3. Capillary permeability increased 7. Adaptive defenses activated 4. Complement activated 5. Clotting reaction walls off region 6. Regional temperature increased Innate Defenses p. 779

9 © 2012 Pearson Education, Inc. Figure 22-14 Pathways of Complement Activation (Part 2 of 3) The most rapid and effective activation of the complement system occurs through the classical pathway. Activation and Cascade C3b Attachment (classical pathway) C3b Attachment (alternate pathway) The classical pathway ends with the conversion of an inactive C3 to an activated C3b that attaches to the cell wall. The attached C1 protein then acts as an enzyme, catalyzing a series of reactions involving other complement proteins. C3b C3 C2 C1 C1 attachment Classical Pathway Antibody Binding and C1 Attachment Antibody binding Antibodies Bacterial cell wall C4 p. 783

10 © 2012 Pearson Education, Inc. Figure 22-14 Pathways of Complement Activation (Part 1 of 3) The alternative pathway is important in the defense against bacteria, some parasites, and virus-infected cells. Alternative Pathway C3 C3b The alternative pathway begins when several complement proteins, notably properdin, interact in the plasma. This interaction can be triggered by exposure to foreign materials, such as the capsule of a bacterium. The end result is the attachment of an activated C3b protein to the bacterial cell wall. Properdin Factor B Factor D Bacterial cell wall p. 783

11 © 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 2 of 2) Complement system consists of circulating proteins that assist antibodies in the destruction of pathogens. is a localized, tissue-level response that tends to limit the spread of an injury or infection. Inflammatory response is an elevation of body temperature that accelerates tissue metabolism and the activity of defenses. Fever Mast cell Complement Lysed pathogen Body temperature rises above 37.2ºC in response to pyrogens 1. Blood flow increased 2. Phagocytes activated 3. Capillary permeability increased 7. Adaptive defenses activated 4. Complement activated 5. Clotting reaction walls off region 6. Regional temperature increased Innate Defenses p. 779

12 © 2012 Pearson Education, Inc. Figure 22-15 Inflammation and the Steps in Tissue Repair (Part 1 of 2) Tissue Damage Mast Cell Activation Chemical change in interstitial fluid Release of histamine and heparin from mast cells p. 784

13 © 2012 Pearson Education, Inc. Figure 22-15 Inflammation and the Steps in Tissue Repair (Part 2 of 2) Redness, Swelling, Warmth, and Pain Phagocyte Attraction Attraction of phagocytes, especially neutrophils Release of cytokines Dilation of blood vessels, increased blood flow, increased vessel permeability Clot formation (temporary repair) Removal of debris by neutrophils and macro- phages; stimulation of fibroblasts Activation of specific defenses Pathogen removal, clot erosion, scar tissue formation Tissue Repair p. 784

14 © 2012 Pearson Education, Inc. Figure 22-11 Innate Defenses (Part 2 of 2) Complement system consists of circulating proteins that assist antibodies in the destruction of pathogens. is a localized, tissue-level response that tends to limit the spread of an injury or infection. Inflammatory response is an elevation of body temperature that accelerates tissue metabolism and the activity of defenses. Fever Mast cell Complement Lysed pathogen Body temperature rises above 37.2ºC in response to pyrogens 1. Blood flow increased 2. Phagocytes activated 3. Capillary permeability increased 7. Adaptive defenses activated 4. Complement activated 5. Clotting reaction walls off region 6. Regional temperature increased Innate Defenses p. 779

15 © 2012 Pearson Education, Inc. Figure 22-17 An Overview of the Immune Response Adaptive Defenses Cell-Mediated Immunity Direct Physical and Chemical Attack Antibody-Mediated Immunity Attack by Circulating Antibodies Destruction of antigens Phagocytes activated T cells activated Communication and feedback Antigen presentation triggers specific defenses, or an immune response. Activated B cells give rise to cells that produce antibodies. Activated T cells find the pathogens and attack them through phagocytosis or the release of chemical toxins. p. 787

16 © 2012 Pearson Education, Inc. Figure 22-16 Forms of Immunity Immunity Response to threats on an individualized basis Adaptive Immunity Active ImmunityPassive Immunity Adaptive immunity is not present at birth; you acquire immunity to a specific antigen only when you have been exposed to that antigen or receive antibodies from another source. Develops in response to antigen exposure Develops after exposure to antigens in environment Develops after administration of an antigen to prevent disease Conferred by transfer of maternal antibodies across placenta or in breast milk Conferred by administration of antibodies to combat infection Naturally acquired active immunity Artificially induced active immunity Naturally acquired passive immunity Artificially induced passive immunity Genetically determined  no prior exposure or antibody production involved Innate Immunity Produced by transfer of antibodies from another source p. 786

17 © 2012 Pearson Education, Inc. Figure 22-18a Antigens and MHC Proteins Antigen presentation by Class I MHC proteins is triggered by viral or bacterial infection of a body cell. The infection results in the appearance of abnormal peptides in the cytoplasm. The abnormal peptides are incorporated into Class I MHC proteins as they are synthesized at the endoplasmic reticulum. Plasma membrane Viral or bacterial pathogen Transport vesicle Endoplasmic reticulum Nucleus The abnormal peptides are displayed by Class I MHC proteins on the plasma membrane. After export to the Golgi apparatus, the MHC proteins reach the plasma membrane within transport vesicles. Infected cell p. 789

18 © 2012 Pearson Education, Inc. Figure 22-18b Antigens and MHC Proteins Antigenic fragments are displayed by Class II MHC proteins on the plasma membrane. Antigenic fragments are bound to Class II MHC proteins. The endoplasmic reticulum produces Class II MHC proteins. Plasma membrane Endoplasmic reticulum Nucleus Lysosome Phagocytic antigen-presenting cell Lysosomal action produces antigenic fragments. Phagocytic APCs engulf the extracellular pathogens. p. 789

19 p. 771 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings© 2012 Pearson Education, Inc.

20 Figure 22-5 Classes of Lymphocytes (Part 1 of 2) Classes of Lymphocytes subdivided into can differentiate into T Cells Approximately 80% of circulating lymphocytes are classified as T cells. Cytotoxic T Cells Helper T Cells Cytotoxic T cells attack foreign cells or body cells infected by viruses. Helper T cells stimulate the activation and function of both T cells and B cells. Suppressor T cells inhibit the activation and function of both T cells and B cells. Memory T cells are a subset of T cells that respond to a previously encountered antigen. Memory T Cells Suppressor T Cells p. 770

21 © 2012 Pearson Education, Inc. Figure 22-5 Classes of Lymphocytes (Part 2 of 2) subdivided into B Cells Plasma Cells When stimulated, B cells can differentiate into plasma cells, which produce and secrete antibodies. B cells make up 10  15% of circulating lymphocytes. NK cells make up the remaining 5  10% of circulating lymphocytes. NK Cells Classes of Lymphocytes p. 770

22 © 2012 Pearson Education, Inc. Figure 22-19 Antigen Recognition by and Activation of Cytotoxic T Cells (Steps 1-3) Antigen Recognition Activation and Cell Division Infected cell Inactive CD8 T cell Viral or bacterial antigen Antigen recognition occurs when a CD8 T cell encounters an appropriate antigen on the surface of another cell, bound to a Class I MHC protein. Antigen recognition results in T cell activation and cell division, producing active T C cells and memory T C cells. Active T C cell Memory T C cells (inactive) Infected cell CD8 protein Class I MHC T cell receptor CD8 T cell Antigen Costimulation activates CD8 T cell Before activation can occur, a T cell must be chemically or physically stimulated by the abnormal target cell. Costimulation p. 790

23 © 2012 Pearson Education, Inc. Figure 22-19 Antigen Recognition by and Activation of Cytotoxic T Cells (Steps 4) Destruction of Target Cells The active T C cell destroys the antigen-bearing cell. It may use several different mechanisms to kill the target cell. Lysed cell Perforin release Destruction of plasma membrane Stimulation of apoptosis Disruption of cell metabolism Cytokine release Lymphotoxin release p. 790

24 © 2012 Pearson Education, Inc. Figure 22-21a A Summary of the Pathways of T Cell Activation Activation by Class I MHC proteins Antigen bound to Class I MHC protein Indicates that the cell is infected or otherwise abnormal CD8 T Cells Cytotoxic T Cells Memory T C Cells Attack and destroy infected and abnormal cells displaying antigen Await reappearance of the antigen Control or moderate immune response by T cells and B cells Suppressor T Cells p. 792

25 © 2012 Pearson Education, Inc. Figure 22-20 Antigen Recognition and Activation of Helper T Cells (Part 1 of 2) Antigen Recognition by CD4 T Cell Foreign antigen Antigen-presenting cell (APC) Class II MHC APC Antigen T cell receptor Costimulation CD4 protein T H cell Inactive CD4 (T H ) cell p. 791

26 © 2012 Pearson Education, Inc. Figure 22-20 Antigen Recognition and Activation of Helper T Cells (Part 2 of 2) CD4 T Cell Activation and Cell Division Memory T H cells (inactive) Active T H cells Cytokines Active helper T cells secrete cytokines that stimulate both cell-mediated and antibody-mediated immunity. Cytokines p. 791

27 © 2012 Pearson Education, Inc. Figure 22-21b A Summary of the Pathways of T Cell Activation Activation by Class II MHC proteins Helper T Cells Stimulate immune response by T cells and B cells Await reappearance of the antigen Memory T H Cells CD4 T Cells Indicates presence of pathogens, toxins, or foreign proteins Antigen bound to Class II MHC protein p. 792

28 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings© 2012 Pearson Education, Inc. p. 771

29 © 2012 Pearson Education, Inc. Figure 22-22 The Sensitization and Activation of B Cells (Step 1) Sensitization Sensitized B cell Antigen binding Antigens bound to antibody molecules Antigens Class II MHC Antibodies Inactive B cell p. 793

30 © 2012 Pearson Education, Inc. Figure 22-22 The Sensitization and Activation of B Cells (Step 2) Activation Cytokine costimulation Helper T cell T cell Sensitized B cell B cell Class II MHC T cell receptor Antigen p. 793

31 © 2012 Pearson Education, Inc. Figure 22-22 The Sensitization and Activation of B Cells (Step 3) Division and Differentiation Plasma cells ANTIBODY PRODUCTION Activated B cells Memory B cells (inactive) p. 793

32 © 2012 Pearson Education, Inc. Figure 22-21b A Summary of the Pathways of T Cell Activation Activation by Class II MHC proteins Helper T Cells Stimulate immune response by T cells and B cells Await reappearance of the antigen Memory T H Cells CD4 T Cells Indicates presence of pathogens, toxins, or foreign proteins Antigen bound to Class II MHC protein p. 792

33 © 2012 Pearson Education, Inc. Figure 22-23a Antibody Structure and Function Antigen binding site Variable segment Constant segments of light and heavy chains Heavy chain Disulfide bond Antigen binding site Light chain Complement binding site Site of binding to macrophages A diagrammatic view of the structure of an antibody. p. 794

34 © 2012 Pearson Education, Inc. Figure 22-23c Antibody Structure and Function Antigen Antigenic determinant sites Antibodies Antibodies bind to portions of an antigen called antigenic determinant sites, or epitopes. p. 794

35 © 2012 Pearson Education, Inc. Figure 22-23d Antibody Structure and Function Antibody molecules can bind a hapten (partial antigen) once it has become a complete antigen by combining with a carrier molecule. Complete antigen Hapten Carrier molecule p. 794

36 © 2012 Pearson Education, Inc. Table 22-1 Classes of Antibodies (Part 1 of 2) p. 795

37 © 2012 Pearson Education, Inc. Table 22-1 Classes of Antibodies (Part 2 of 2) Secretory piece p. 795

38 © 2012 Pearson Education, Inc. Figure 22-24a The Primary and Secondary Responses in Antibody-Mediated Immunity Time (weeks) IgG IgM Antibody concentration in serum PRIMARY RESPONSE p. 796

39 © 2012 Pearson Education, Inc. Figure 22-24b The Primary and Secondary Responses in Antibody-Mediated Immunity Time (weeks) IgM SECONDARY RESPONSE IgG p. 796

40 © 2012 Pearson Education, Inc. Figure 22-25 The Course of the Body’s Response to a Bacterial Infection Neutrophils Macrophages Plasma cells Antibody titer Cytotoxic T cells Natural killer cells Time (weeks) Number of active immune cells p. 797

41 p. 798 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2012 Pearson Education, Inc.

42 Figure 22-27a Defenses against Bacterial and Viral Pathogens BACTERIA Phagocytosis by macrophages and APCs Antigen presentation Activation of cytotoxic T cells Activation of helper T cells Activation of B cells Antibody production by plasma cells Destruction of bacteria by cell lysis or phagocytosis Opsonization and phagocyte attraction Formation of antigen  antibody complexes Defenses against bacteria involve phagocy- tosis and antigen presentation by APCs. p. 799

43 © 2012 Pearson Education, Inc. Figure 22-27b Defenses against Bacterial and Viral Pathogens Release of interferons Infection of tissue cells Appearance of antigen in plasma membrane Infection of or uptake by APCs VIRUSES Antigen presentation Activation of helper T cells Activation of B cells Antibody production by plasma cells Destruction of viruses or prevention of virus entry into cells Increased resistance to viral infection and spread Stimulation of NK cells Activation of cytotoxic T cells Destruction of virus-infected cells Defenses against viruses involves direct contact with virus-infected cells and antigen presentation by APCs. p. 799

44 © 2012 Pearson Education, Inc. Figure 22-29 The Mechanism of Anaphylaxis (Part 1 of 2) First Exposure Allergen fragment Allergens Macrophage B cell sensitization and activation T H cell activation Plasma cell IgE antibodies p. 804

45 © 2012 Pearson Education, Inc. Figure 22-29 The Mechanism of Anaphylaxis (Part 2 of 2) IgE Granules Massive stimulation of mast cells and basophils Sensitization of mast cells and basophils Subsequent Exposure Release of histamines, leukotrienes, and other chemicals that cause pain and inflammation Capillary dilation, increased capillary permeability, airway constriction, mucus secretion, pain and itching Allergen p. 804


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