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The Human Body in Health and Illness, 4th edition
Barbara Herlihy
Chapter 21:Immune System
1
Lesson 21-1 Objectives
• Differentiate between specific and nonspecific immunity.
• Describe the process of phagocytosis.• Explain the causes of the signs of
inflammation.• Explain the role of fever in fighting infection.• Explain the role of T cells in cell-mediated
immunity.Copyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights reserved.
2
Lesson 21-1 Objectives (cont’d.)
• Explain the role of B cells in antibody-mediated immunity.
• Differentiate between genetic immunity and acquired immunity.
• Describe naturally and artificially acquired active and passive immunity.
• Identify the steps in the development of anaphylaxis.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.3
Immune System: Classification
• Specific immunity protects against one substance.
• Nonspecific immunity protects against many substances.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.4
Immunity: Lines of Defense
• Nonspecific immunity– First line: Mechanical or chemical barriers, reflexes– Second line: Phagocytosis, inflammation, fever,
protective proteins, natural killer cells
• Specific immunity– Third line: B and T lymphocytes or B and T cells
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.5
Nonspecific Immunity: Lines of Defense
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.6
Second Line of Defense: Phagocytosis
• Leukocytes go to site of infection.– Diapedesis– Chemotaxis
• Leukocytes “eat”– Pathogens – Cellular debris
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.7
Second Line of Defense: Inflammation
• Classic signs– Redness– Heat – Swelling– Pain
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.8
Second Line of Defense: Fever (Pyrexia)
• Phagocytosis releases pyrogens.
• Pyrogens reset body thermostat upward.
• Body temperature rises.
• Antipyretics can lower temperature.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.9
Second Line of Defense: Protective Proteins
• Interferons are secreted by cells infected by a virus.
• Interferons protect other cells from viral replication.
• Complement proteins assist WBCs.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.10
Second Line of Defense: NK Cells
• A lymphocyte that acts nonspecifically
• Effective against many microbes and certain cancer cells
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.11
Specific Immunity: 3rd Line of Defense
• T cells– Cell-mediated
immunity
• B cells– Antibody-mediated
immunity
• Macrophages– Help activate T and B
cellsCopyright © 2011, 2007 by Saunders,
an imprint of Elsevier Inc. All rights reserved.
12
T-Cell Activation• Macrophage
ingests antigen• Antigen
presentation• Clone produced
– Killer T cells– Helper T cells– Suppressor T cells– Memory T cells
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.13
B-Cell Activation• Macrophage
ingests antigen• Antigen
presentation• B cells and helper T
cells activated• Clone formed
– Plasma cells– Memory B cells
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.14
Antigen, Antibody, Immunoglobulin• Antigen: Stimulates formation of antibodies • Antibody: Secreted by B cells, also called
immunoglobulins• Antigen-antibody interaction agglutination• Important immunoglobulins
– Immunoglobulin G (IgG)– Immunoglobulin A (IgA)– Immunoglobulin M (IgM)– Immunoglobulin E (IgE)
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.15
Why is Secondary Response Stronger than Primary Response?
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.16
Types of Immunity
• Genetic: Inborn and species-specific
• Acquired: How do you get it?– Naturally– Artificially
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.17
Naturally Acquired Immunity • Active: You are
exposed to the antigen and you produce antibodies.– Exposure to a virus
• Passive: Someone else makes antibodies.– From mother
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.18
Artificially Acquired Immunity
• Active– Vaccines– Toxoids
• Passive– Immune globulin
(antibodies made by others)
– Antitoxins, antivenoms
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.19
Allergic Reaction: Delayed
• Occurs in about 48 hours• Usual cause is repeated exposure of skin to
irritants (household detergents, poison ivy)• Activates T cells, causing skin eruptions and
inflammation (contact dermatitis)
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.20
Immediate Hypersensitivity Reaction: Anaphylaxis
• Bee venom IgE • IgE binds to mast cells.• Second sting: Venom
binds to IgE on mast cell.
• Mast cells release histamine.
• Histamine drops BP and impairs breathing.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.21
Other Immunological Responses
• Autoimmune diseases: Develop in response to self-attack, or autoimmunity
• Organ rejection: Recipient’s immune system recognizes donated organ as foreign, mounts immune attack against it
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.22