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Lymphatic system and body defenses

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Presentation on theme: "Lymphatic system and body defenses"— Presentation transcript:

1 Lymphatic system and body defenses
Nonspecific defenses Do not distinguish one type of threat from another 7 types Specific defenses Protect against particular threats Depend upon the activation of lymphocytes

2 SECTION 22-3 Nonspecific Defenses

3 Nonspecific Defenses, Physical barriers
Keep hazardous organisms outside the body Includes hair, epithelia, secretions of integumentary and digestive systems

4 Figure 22.10 Nonspecific Defenses (Part 1 - Physical Barriers)

5 Nonspecific Defenses, Phagocytes
Remove cellular debris and respond to invasion by foreign pathogens Monocyte-macrophage system - Fixed and free Microphages – Neutrophils and eosinophils Move by diapedesis Exhibit chemotaxis

6 Figure 22.10 Nonspecific Defenses (Part 2 - Phagocytes)

7 Nonspecific Defenses, Immunological surveillance
Constant monitoring of normal tissue by NK cells NK cells Recognize cell surface markers on foreign cells Destroy cells with foreign antigens

8 NK cell activation Recognition of unusual surface proteins
Rotation of the Golgi toward the target cell and production of perforins Release of perforins by exocytosis Interaction of perforins causing cell lysis

9 Figure 22.10 Nonspecific Defenses (Part 3 - Immunological Surveillance)

10 Figure 22.11 How Natural Killer Cells Kill Cellular Targets

11 Nonspecific Defenses, Interferons (cytokines)
Small proteins released by virally infected cells Trigger the production of antiviral proteins Three major types of interferons are: Alpha– produced by leukocytes and attract/stimulate NK cells Beta– secreted by fibroblasts causing slow inflammation Gamma – secreted by T cells and NK cells stimulate macrophage activity

12 Figure 22.10 Nonspecific Defenses (Part 4 - Interferons)

13 Nonspecific Defenses, Complement system
Cascade of ~11 plasma complement proteins (C) Destroy target cell membranes Stimulate inflammation Attract phagocytes Enhance phagocytosis

14 Complement proteins interact with on another via two pathways
Classical Alternative

15 Figure 22.10 Nonspecific Defenses (Part 5 - Complement System)

16 Figure 22.12 Complement Activation

17 Nonspecific Defenses, Inflammation
Localized tissue response to injury producing Swelling Redness Heat Pain Effects of inflammation include Temporary repair of injury Slowing the spread of pathogens Mobilization of local, regional, and systemic defenses

18 Figure 22.10 Nonspecific Defenses (Part 6 - Inflammatory Response)

19 Figure Inflammation Figure 22.13

20 Nonspecific Defenses, Fever
Maintenance of a body temperature above 37.2oC (99oF) Pyrogens reset the hypothalamic thermostat and raise body temperature Pathogens, toxins, antigen-antibody complexes can act as pyrogens

21 Figure 22.10 Nonspecific Defenses (Part 7 - Fever)

22 SECTION 22-4 Specific Defenses

23 Forms of immunity Innate immunity Genetically determined
Present at birth Acquired immunity Not present at birth Achieved by exposure to antigen Active immunity Passive immunity

24 Figure 22.14 Types of Immunity

25 Properties of immunity
Specificity – activated by and responds to a specific antigen Versatility – is ready to confront any antigen at any time Memory – “remembers” any antigen it has encountered Tolerance – responds to foreign substances but ignores normal tissues

26 The immune system response
Antigen triggers an immune response Activates T cells and B cells T cells are activated after phagocytes exposed to antigen T cells attack the antigen and stimulate B cells Activated B cells mature and produce antibody Antibody attacks antigen

27 Figure 22.15 An Overview of the Immune Response

28 SECTION 22-5 T cells and Cell-mediated Immunity

29 Major types of T cells Cytotoxic T cells (TC) – attack foreign cells
Helper T cells (TH) – activate other T cells and B cells Suppressor T cells (TS) – inhibit the activation of T and B cells

30 Antigen presentation Antigen-glycoprotein combination appears on a cell membrane Called MHC proteins (Major Histocompatibility Complex) Coded for by genes of the MHC T-cells sensitive to the antigen are activated upon contact

31 MHC classes Class I – found on all nucleated cells
Class II – found on antigen presenting cells and lymphocytes

32 Lymphocytes respond to antigens bound to either class I or class II MHC proteins
Antigen recognition T cell membranes contain CD markers CD3 markers present on all T cells CD8 markers on cytotoxic and suppressor T cells CD4 markers on helper T cells

33 Figure 22.16 Antigens and MHC Proteins

34 Figure 22.16 Antigens and MHC Proteins

35 Figure 22.16 Antigens and MHC Proteins
Figure 22.16b

36 Activation of CD8 cells Responds quickly giving rise to other T cells
Cytotoxic T cells – seek out and destroy abnormal cells lymphotoxin Memory TC cells – function during a second exposure to antigen Suppressor T cells – suppress the immune response

37 Figure 22.17 Antigen Recognition and the Activation of Cytotoxic T Cells

38 Figure 22.17 Antigen Recognition and the Activation of Cytotoxic T Cells
PLAY Animation: Cytotoxic T Cell Activation Figure 22.17

39 Activation of CD4 T cells by antigens presented on class II MHC proteins
Produces helper T cells and memory T cells Activated helper T cells Secrete lymphokines that coordinate specific and nonspecific defenses Enhance nonspecific defenses Stimulate the activity of NK cells Promote activation of B cells

40 Figure 22.18 Antigen Recognition and Activation of Helper T cells
PLAY Animation: Antigen Recognition and Helper T Cell Activation Figure 22.18

41 Figure 22.19 A Summary of the Pathways of T Cell Activation

42 The Lymphatic System and Immunity
Chapter 22, part 4 The Lymphatic System and Immunity

43 SECTION 22-6 B Cells and Antibody-mediated Immunity

44 B cell sensitization of activation
Sensitization – the binding of antigens to the B cell membrane antibodies Antigens then displayed on B cell Class II MHC TH cells activated by same antigen stimulate B cell Active B cell differentiates into Memory B Cell or Plasma cell Plasma cells synthesize and release antibody

45 Figure 22.20 The Sensitization and Activation of B Cells
PLAY Animation: B Cells and Antibody Production Figure 22.20

46 Antibodies structure Antibodies are Y-shaped proteins consisting of:
Two parallel polypeptide chains Heavy chains and light chains Constant region and variable region Antigen binding site

47 Figure 22.21 Antibody Structure

48 Figure 22.21 Antibody Structure

49 Figure 22.21 Antibody Structure
Figure 22.21b-d

50 Actions of antibodies include:
Neutralization Agglutination and precipitation Activation of complement Attraction of phagocytes Opsinization Stimulation of inflammation Prevention of adhesion

51 Classes of Antibodies (immunoglobins)
IgG – resistance against many viruses, bacteria and bacterial toxins IgE – accelerates local inflammation IgD – found on the surface of B cells IgM – first type secreted after antigen arrives IgA – primarily found in glandular sec

52 Primary and secondary antibody response
Primary response Takes about two weeks to develop Produced by plasma cells Secondary response Rapid increase in IgG Maximum antibody titer app

53 Figure 22.22 The Primary and Secondary Immune Responses

54 Figure 22.23 An Integrated Summary of the Immune Response

55 Figure 22.25 The Course of the Body’s Response to Bacterial Infection
Figure 22.25a, b

56 SECTION 22-7 Normal and Abnormal Resistance

57 Development of the Immune Response
Immunological competence The ability to demonstrate an immune response after exposure to an antigen Fetuses receive immunity from the maternal bloodstream Infants acquire immunity following exposure

58 Immune disorders Autoimmune disorders
Immune response mistakenly targets normal cells Immunodeficiency diseases Immune system does not develop properly or is blocked

59 Allergies Inappropriate or excessive immune response to allergens
Anaphylaxis Circulating allergen affects mast cells throughout body

60 Figure 22.26 The Mechanism of Anaphylaxis

61 Stress and the immune response
Interleukin-1 released by active macrophages Triggers release of ACTH resulting in glucocorticoid release Moderates the immune response Lowers resistance to disease

62 Stress can cause the following:
Depression of the inflammatory response Phagocytic reduction Inhibition of interleukin secretion

63 You should now be familiar with:
The structure and function of lymphatic cells, tissues and organs The body’s nonspecific defenses and the components and mechanisms of each Specific resistance, cell-mediated immunity and antibody mediated immunity The role of the T cell, B cell and antibodies in specific immunity

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