1. Slides 1 to 87
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2. Lymphatic System Organization
Lymphatic System Definitions
Pathogens—Organisms that cause disease
Lymphatic System—Cells, tissues, and organs that play a central role in the body’s defenses against pathogens
Lymphatic system consists of vessels (lymphatics) filled with lymph connected to lymphatic organs
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3. Lymphatic System Organization
The Components of the Lymphatic System
Figure 14-1

4. Lymphatic System Organization
Functions of the Lymphatic System
Produce, maintain, distribute lymphocytes
Lymphocytes attack invading organisms, abnormal cells, foreign proteins
Maintain blood volume
Help eliminate local variations in interstitial fluid concentration
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5. Lymphatic System Organization
Lymphatic Vessels
Lymph flows inside
Begin as lymphatic capillaries in the tissues
Lymph empties into venous system
At thoracic duct
At right lymphatic duct
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6. Lymphatic System Organization
Lymphatic Capillaries
Figure 14-2(a)

7. Lymphatic System Organization
Lymphatic Capillaries
Figure 14-2(b)

8. Lymphatic System Organization
The Lymphatic Ducts and the Venous System
Figure 14-3

9. Lymphatic System Organization
Three Classes of Lymphocytes
T cells
Thymus dependent
B cells
Bone marrow derived
NK cells
Natural killer
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10. Lymphatic System Organization
Types of T Lymphocytes
Cytotoxic T cells
Provide cell-mediated immunity
Attack foreign and virus-infected cells
Regulatory T cells
Helper T cells
Suppressor T cells
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11. Lymphatic System Organization
B Lymphocytes
Can become plasma cells
Specific to a particular antigen
Produce antibodies that react
with that antigen
Antibodies are immunoglobulins
Responsible for humoral or antibody-mediated immunity
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12. Lymphatic System Organization
NK Lymphocytes
Provide immunological surveillance
Attack cells
Foreign cells
Virally-infected cells
Cancerous cells
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13. Lymphatic System Organization
Lymphocyte Life Cycle
Continuously migrate between lymphoid tissues and the blood
Production and development (called lymphopoiesis) involves:
Bone marrow
Thymus
Peripheral lymphoid tissues
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14. Lymphatic System Organization
The Origins of Lymphocytes
Figure 14-4

15. Lymphatic System Organization
Lymphoid Nodules
Consists of loose connective tissue containing densely packed lymphocytes
Tonsils are lymphoid nodules in the pharynx wall
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16. Lymphatic System Organization
The Tonsils
Figure 14-5

17. Lymphatic System Organization
Lymphoid Organs
Important lymphoid organs include:
Lymph nodes
Thymus
Spleen
Located in areas that are vulnerable to pathogens
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18. Lymphatic System Organization
Lymph Nodes
Encapsulated masses of lymphoid tissue containing lymphocytes
Monitor and filter lymph
Remove antigens
Initiate immune response
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19. Lymphatic System Organization
The Structure of a Lymph Node
Figure 14-6

20. Lymphatic System Organization
The Thymus
Lies behind sternum
T cells divide and mature there
Shrinks after puberty
Produces thymosins
Hormones that regulate T cell development
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21. Lymphatic System Organization
The Thymus
Figure 14-7

22. Lymphatic System Organization
The Thymus
Figure 14-7(a)

23. Lymphatic System Organization
The Thymus
Figure 14-7(b)

24. Lymphatic System Organization
The Thymus
Figure 14-7(c)

25. Lymphatic System Organization
The Spleen
White pulp
Resembles lymphoid nodules
Removes antigens
Initiates immune response
Red pulp
Contains red blood cells
Recycles damaged or out-dated RBCs
Stores iron from recycled RBCs
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26. Lymphatic System Organization
The Spleen
Figure 14-8

27. Lymphatic System Organization
The Spleen
Figure 14-8(a)

28. Lymphatic System Organization
The Spleen
Figure 14-8(b)

29. Lymphatic System Organization
Overview of Body’s Defenses
Non-specific defenses
Protect against any threat
Specific defenses
Protect against particular threats
Responds to antigens
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30. Nonspecific Defenses Physical Barriers Skin, hair, & skin secretions
Digestive epithelia, & secretions
Figure 14-9 (1 of 7)

31. Nonspecific Defenses Phagocytes Microphages (neutrophils, eosinophils)
Macrophages
Figure 14-9 (2 of 7)

32. Nonspecific Defenses Immunological Surveillance NK cells
Find, kill cancer and virus-infected cells
Figure 14-9 (3 of 7)

33. Nonspecific Defenses Interferons
Small proteins released by virus-infected cells
Cytokines that trigger release of anti-viral proteins that inhibit virus production
Figure 14-9 (4 of 7)

34. Nonspecific Defenses Complement System Complex system of proteins
Initiate chain reaction (positive feedback)
Destroy target cell membranes
Stimulate inflammation, attract phagocytes
Figure 14-9 (5 of 7)

35. Nonspecific Defenses Inflammatory Response
Coordinated non-specific response to tissue injury
Figure 14-9 (6 of 7)

36. Nonspecific Defenses Fever Temperature greater than 99ºF
Inhibits pathogens
Accelerates metabolism
Figure 14-9 (7 of 7)

37. Events in Inflammation
Nonspecific Defenses
Events in Inflammation
Figure 14-10

38. Specific Defenses: Immunity
Types of Immunity
Innate immunity
Genetically determined
Present at birth
Acquired immunity
Active
Follows exposure to antigen
Passive
From transfer of antibodies from outside source
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39. Specific Defenses: Immunity
Types of Immunity
Figure 14-11

40. Specific Defenses: Immunity
Properties of Specific Immunity
Provided by lymphocytes
Four general characteristics
Specificity
Versatility
Memory
Tolerance
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41. Specific Defenses: Immunity
Properties of Specific Immunity
Specificity
T and B cell membrane receptors recognize a unique antigen
Versatility
Responsive to millions of antigens
Memory
Memory cells recall earlier encounters with an antigen
Tolerance
Ignores body’s own antigens
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42. Specific Defenses: Immunity
Overview of the Immune Response
Purpose is to inactivate or destroy:
Pathogens
Abnormal cells
Foreign molecules
Based on activation of lymphocytes by specific antigens by antigen recognition
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43. CELL–MEDIATED IMMUNITY ANTIBODY–MEDIATED IMMUNITY
Direct
physical and
chemical
attack
CELL–MEDIATED IMMUNITY
ANTIGENS
Phagocytes
activated
T cells
activated
SPECIFIC
DEFENSES
(Immune
response)
Bacteria
Communication
and feedback
ANTIBODY–MEDIATED IMMUNITY
Viruses
B cells
activated
Attack by
circulating
antibodies
Figure 14-12
1 of 7
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44. ANTIGENS Bacteria Viruses Figure 14-12 2 of 7
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45. ANTIGENS SPECIFIC DEFENSES (Immune response)
Bacteria
Viruses
Figure 14-12
3 of 7
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46. CELL–MEDIATED IMMUNITY
ANTIGENS
Phagocytes
activated
T cells
activated
SPECIFIC
DEFENSES
(Immune
response)
Bacteria
Viruses
Figure 14-12
4 of 7
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47. CELL–MEDIATED IMMUNITY ANTIBODY–MEDIATED IMMUNITY
ANTIGENS
Phagocytes
activated
T cells
activated
SPECIFIC
DEFENSES
(Immune
response)
Bacteria
Communication
and feedback
ANTIBODY–MEDIATED IMMUNITY
Viruses
B cells
activated
Figure 14-12
5 of 7
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48. CELL–MEDIATED IMMUNITY ANTIBODY–MEDIATED IMMUNITY
Direct
physical and
chemical
attack
CELL–MEDIATED IMMUNITY
ANTIGENS
Phagocytes
activated
T cells
activated
SPECIFIC
DEFENSES
(Immune
response)
Bacteria
Communication
and feedback
ANTIBODY–MEDIATED IMMUNITY
Viruses
B cells
activated
Figure 14-12
6 of 7
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49. CELL–MEDIATED IMMUNITY ANTIBODY–MEDIATED IMMUNITY
Direct
physical and
chemical
attack
CELL–MEDIATED IMMUNITY
ANTIGENS
Phagocytes
activated
T cells
activated
SPECIFIC
DEFENSES
(Immune
response)
Bacteria
Communication
and feedback
ANTIBODY–MEDIATED IMMUNITY
Viruses
B cells
activated
Attack by
circulating
antibodies
Figure 14-12
7 of 7
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50. Specific Defenses: Immunity
T Cell Activation
Antigens processed by macrophages
Fragments form complex with MHC proteins on cell surface
T cell recognizes MHC complex, or
Viral antigens on infected body cells
Activated T cells differentiate further
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51. Specific Defenses: Immunity
Roles for Activated T Cells
Cytotoxic (killer) T cells
Provide cell-mediated immunity
Memory T cells
Remember the activating antigen
Suppressor T cells
Suppress other T and B cells
Helper T cells
Secrete regulatory cytokines
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52. ACTIVATION AND Infected cell CELL DIVISION Memory T cells (inactive)
Viral or
bacterial
antigen
Class I
MHC protein
Active cytotoxic
T cells
T cell
receptor
Inactive
cytotoxic
T cell
Lymphotoxin
release
Cytokine
release
Perforin
release
Destruction
of cell
membrane
Disruption
of cell
metabolism
Stimulation
of apoptosis
Figure 14-13
1 of 5
Lysed
cell
DESTRUCTION
OF TARGET CELL
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53. Infected cell Viral or bacterial antigen Class I MHC protein T cell
receptor
Inactive
cytotoxic
T cell
Figure 14-13
2 of 5
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54. ACTIVATION AND CELL DIVISION Memory T cells (inactive)
Infected cell
Memory T
cells (inactive)
Viral or
bacterial
antigen
Class I
MHC protein
Active cytotoxic
T cells
T cell
receptor
Inactive
cytotoxic
T cell
Figure 14-13
3 of 5
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55. ACTIVATION AND CELL DIVISION Memory T cells (inactive)
Infected cell
Memory T
cells (inactive)
Viral or
bacterial
antigen
Class I
MHC protein
Active cytotoxic
T cells
T cell
receptor
Inactive
cytotoxic
T cell
Lymphotoxin
release
Cytokine
release
Perforin
release
Destruction
of cell
membrane
Disruption
of cell
metabolism
Stimulation
of apoptosis
Figure 14-13
4 of 5
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56. ACTIVATION AND Infected cell CELL DIVISION Memory T cells (inactive)
Viral or
bacterial
antigen
Class I
MHC protein
Active cytotoxic
T cells
T cell
receptor
Inactive
cytotoxic
T cell
Lymphotoxin
release
Cytokine
release
Perforin
release
Destruction
of cell
membrane
Disruption
of cell
metabolism
Stimulation
of apoptosis
Figure 14-13
5 of 5
Lysed
cell
DESTRUCTION
OF TARGET CELL
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57. Specific Defenses: Immunity
Key Note
Cell-mediated immunity depends on direct contact between cytotoxic T cells and foreign, abnormal, or infected cells. T cell activation usually involves antigen presentation by a phagocytic cell. Cytotoxic T cells destroy target cells with cytokines, lymphotoxins,
or perforin.
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58. Specific Defenses: Immunity
B Cells and Antibody-Mediated Immunity
B cells are first sensitized by exposure
to “their” antigen
Helper T cells for that antigen then activate those B cells
Activated B cells divide to form:
Plasma cells
Produce antibodies against that antigen
Memory cells
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59. Division and differentiation
Sensitization
Activation
Division and differentiation
Class II
MHC
Antigens
T cell receptor
Antigen
Class II MHC
ANTIBODY
PRODUCTION
Antibodies B
cell T
cell
Inactive B cell
Antigens bound to
antibody molecules
Stimulation
by cytokines
Plasma cells
Antigen
binding
Sensitized
B cell
Helper T cell
Activated B cells
Sensitized
B cell
Memory B cells
(inactive)
Figure 14-14
1 of 5
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60. Sensitization Figure 14-14 2 of 5 Antigens Class II MHC Antibodies
Inactive B cell
Antigens bound to
antibody molecules
Antigen
binding
Sensitized
B cell
Figure 14-14
2 of 5
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61. Sensitization Activation Figure 14-14 3 of 5 Class II MHC Antigens
T cell receptor
Antigen
Class II MHC
Antibodies B
cell T
cell
Inactive B cell
Antigens bound to
antibody molecules
Antigen
binding
Sensitized
B cell
Helper T cell
Sensitized
B cell
Figure 14-14
3 of 5
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62. Division and differentiation
Sensitization
Activation
Division and differentiation
Class II
MHC
Antigens
T cell receptor
Antigen
Class II MHC
Antibodies B
cell T
cell
Inactive B cell
Antigens bound to
antibody molecules
Stimulation
by cytokines
Antigen
binding
Sensitized
B cell
Helper T cell
Activated B cells
Sensitized
B cell
Memory B cells
(inactive)
Figure 14-14
4 of 5
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63. Division and differentiation
Sensitization
Activation
Division and differentiation
Class II
MHC
Antigens
T cell receptor
Antigen
Class II MHC
ANTIBODY
PRODUCTION
Antibodies B
cell T
cell
Inactive B cell
Antigens bound to
antibody molecules
Stimulation
by cytokines
Plasma cells
Antigen
binding
Sensitized
B cell
Helper T cell
Activated B cells
Sensitized
B cell
Memory B cells
(inactive)
Figure 14-14
5 of 5
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64. Specific Defenses: Immunity
Antibody Structure and Function
Two pairs of parallel polypeptide chains
Four Fixed segments
Provides basic structure
Four Variable segments
Provides specific antigen-binding structure
Antigen-antibody complex forms
Antigen determinant site binds to antibody
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65. Specific Defenses: Immunity
Antibody Structure
Figure 14-15

66. Specific Defenses: Immunity
Classes of Antibodies
Immunoglobulin G (IgG)
Resistance to pathogens
Immunoglobulin M (IgM)
First antibody secreted
Immunoglobulin A (IgA)
Found in glandular secretions
Immunoglobulin E (IgE)
Stimulates inflammation
Immunoglobulin D (IgD)
Found on surface of B cells
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67. Specific Defenses: Immunity
How Antibodies Can Eliminate Antigens
Neutralization
Precipitation
Agglutination
Complement activation
Attraction of phagocytes
Stimulation of phagocytosis
Stimulation of inflammation
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68. Specific Defenses: Immunity
Key Note
Antibody-mediated immunity depends on specific antibodies from plasma cells derived from activated B cells by (1) antigen recognition, through binding to surface antibodies, and (2) stimulation by a helper T cell activated by the same antigen. The antibodies bind to the target antigen and either inhibit it, destroy it, remove it from solution, or promote its phagocytosis.
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69. Specific Defenses: Immunity
Primary and Secondary Immune Response
Primary response—Antibodies produced by plasma cells after first exposure to antigen
Secondary response—Maximum antibody levels produced by subsequent exposure to the same antibody
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70. Specific Defenses: Immunity
The Primary and Secondary
Immune Responses
Figure 14-16

71. Specific Defenses: Immunity
Key Note
Immunization produces a primary response to a specific antigen. If the same antigen is encountered at a later date, it triggers a powerful secondary response that usually prevents infection and disease.
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72. Specific Defenses: Immunity
Hormones of the Immune System
Interleukins (IL)
Sensitize T cells
Stimulate B cells
Enhance non-specific defenses
Interferons
Slow the spread of viruses locally
Tumor necrosis factors (TNF)
Slows growth, kills tumor cells
Phagocytic regulators
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73. Specific Defenses: Immunity
Key Note
Viruses replicate inside cells, whereas bacteria usually live outside. Antibodies work outside of cells, so they are primarily effective against bacteria rather than viruses. T cells, NK cells, and interferons are the primary defenses against viral infection.
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74. Patterns of Immune Response
A Summary of the Immune Response and Its Relationship to Nonspecific Defenses
Figure 14-17

75. Patterns of Immune Response
Immune Disorders
Autoimmune disorders
Mistaken attack on body’s own tissues
Immunodeficiency disease
Disease (e.g., AIDS) or a congenital block of immunity
Allergies
Inappropriate or excessive response to allergens
Age-related loss of effectiveness
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76. Patterns of Immune Response
Types of Allergies
Immediate hypersensitivity (Type I)
Cytotoxic reaction (Type II)
Immune complex disorders (Type III)
Delayed hypersensitivity (Type IV)
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77. The Lymphatic System in Perspective
FIGURE Functional Relationships Between the Lymphatic System and Other Systems
Figure 14-18
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78. The Integumentary System
Provides physical barriers to pathogen entry; macrophages in dermis resist infection and present antigens to trigger immune response; mast cells trigger inflammation, mobilize cells of lymphatic system
Provides IgA antibodies for secretion onto integumentary surfaces
Figure 14-18
2 of 11
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79. The Skeletal System
Lymphocytes and other cells involved in the immune response are produced and stored in bone marrow
Assists in repair of bone after injuries; macrophages fuse to become osteoclasts
Figure 14-18
3 of 11
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80. The Muscular System
Protects superficial lymph nodes and the lymphatic vessels in the abdominopelvic cavity; muscle contractions help propel lymph along lymphatic vessels
Assists in repair after injuries
Figure 14-18
4 of 11
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81. The Nervous System
Microglia present antigens that stimulate specific defenses; glial cells secrete cytokines; innervation stimulates antigen-presenting cells
Cytokines affect hypothalamic production of CRH and TRH
Figure 14-18
5 of 11
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82. The Endocrine System
Glucocorticoids have anti-inflammatory effects; thymosins stimulate development and maturation of lymphocytes; many hormones affect immune function
Thymus secretes thymosins; cytokines affect cells throughout the body
Figure 14-18
6 of 11
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83. The Cardiovascular System
Distributes WBCs; carries antibodies that attack pathogens; clotting response helps restrict spread of pathogens; granulocytes and lymphocytes produced in bone marrow
Fights infections of cardiovascular organs; returns tissue fluid to circulation
Figure 14-18
7 of 11
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84. The Respiratory System
Alveolar phagocytes present antigens and trigger specific defenses; provides oxygen required by lymphocytes and eliminates carbon dioxide generated during their metabolic activities
Tonsils protect against infection at entrance to respiratory tract
Figure 14-18
8 of 11
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85. The Digestive System
Provides nutrients required by lymphatic tissues; digestive acids and enzymes provide nonspecific defense against pathogens
Tonsils and lymphoid nodules of the intestine defend against infection and toxins absorbed from the digestive tract; lymphatics carry absorbed lipids to venous system
Figure 14-18
9 of 11
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86. The Urinary System
Eliminates metabolic wastes generated by cellular activity; acid pH of urine provides nonspecific defense against urinary tract infection
Provides specific defenses against urinary tract infections
Figure 14-18
10 of 11
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87. The Reproductive System
Lysozymes and bactericidal chemicals in secretions provide nonspecific defense against reproductive tract infections
Provides IgA antibodies for secretion by epithelial glands
Figure 14-18
11 of 11
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