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How The Animal Body Defends Itself

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1 How The Animal Body Defends Itself
Chapter 25 Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

2 Evolution of Immune System Initiating Immune Response
Outline First Line of Defense Second Line of Defense Third Line of Defense Evolution of Immune System Initiating Immune Response T Cell Cellular Response B Cell Humoral Response Vaccination Immune System Failure Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

3 Skin - “Walls and Moats” Cellular Counterattack - “Roaming Patrols”
Overview Three Lines Of Defense Skin - “Walls and Moats” Cellular Counterattack - “Roaming Patrols” Immune System - “Sentries” Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

4 Stratum Corneum - outer layer Basal Layer - innermost layer
First Line of Defense Skin is largest organ, and provides first line of defense against microbe invasion. Three Layers Epidermis 10-30 cells thick Stratum Corneum - outer layer Basal Layer - innermost layer Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

5 15-40 times thicker than epidermis.
First Line of Defense Dermis 15-40 times thicker than epidermis. Provides structural support for epidermis. Subcutaneous Layer Composed of fat-rich cells acting as shock absorbers and insulators. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

6 Section of Human Skin Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

7 Other External Surfaces Digestive Tract Saliva Acidic Environment
First Line of Defense Other External Surfaces Digestive Tract Saliva Acidic Environment Respiratory Tract Mucosal Layer Cilia Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

8 Four main cellular and chemical defenses:
Second Line of Defense Four main cellular and chemical defenses: Cells that kill invading microbes Proteins that kill invading microbes Inflammatory response Temperature response Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

9 White Blood Cells That Kill Invading Microbes
Second Line of Defense White Blood Cells That Kill Invading Microbes Macrophages - Ingest bacteria. Neutrophils - Release chemicals. Natural Killer Cells - Attack body cells infected by invading microbes. Puncture membrane Body’s cells contain self-identifying MHC proteins. Autoimmune Diseases Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

10 Proteins That Kill Invading Microbes Complement System
Second Line of Defense Proteins That Kill Invading Microbes Complement System Approximately 20 proteins circulate freely in blood plasma. Aggregate to form membrane attack complex. Insert into cell’s plasma membrane and form pore allowing water to rush in and burst cell membrane. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

11 Inflammatory Response
Second Line of Defense Inflammatory Response Injured cells release chemical alarm signals (histamine and prostaglandins) that cause blood vessels to expand. Increases blood flow to site of injury. Stretches capillary walls increasing permeability. Redness and Swelling Phagocyte Migration Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

12 Local Inflammation Copyright © McGraw-Hill Companies Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

13 Fever inhibits microbial growth.
Second Line of Defense Temperature Response When macrophages initiate counterattack, they send a message to brain to raise body temperature. Fever inhibits microbial growth. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

14 Involve actions of leukocytes T and B Cells are lymphocytes.
Third Line of Defense Involve actions of leukocytes T and B Cells are lymphocytes. T Cells originate in bone marrow and migrate to thymus. Develop ability to identify foreign particles by antigens exposed on their surfaces. Antigen is any molecule provoking specific immune response. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

15 Inducer - oversee T cell development.
Third Line of Defense T Cells Inducer - oversee T cell development. Helper - initiate immune response. Cytotoxic - lyse infected cells. Supressor - terminate immune response. B Cells Complete maturation in bone marrow. Circulate in blood and lymph. Produce antibodies. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

16 Evolution of Immune System
Bacteria Defend against viral invasion through restriction endonucleases that degrade foreign DNA lacking specific DNA pattern. Invertebrates Mark cell surfaces with self labels. Employ negative test. May not recognize cells that resemble self marker as foreign. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

17 Evolution of Immune System
Shared Elements of Invertebrate and Vertebrate Immune Responses Phagocytes Distinguishing Self from Non-Self Lymphocytes Antibodies Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

18 Evolution of Immune System
Vertebrates Modern vertebrate immune system first arose in fish with jaws. Sharks are oldest surviving group. Have immune response much like that in mammals. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

19 Copyright © McGraw-Hill Companies
Permission required for reproduction or display Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

20 Initiating Immune Response
Macrophages inspect surfaces of cells encountered for MHC proteins. T cells only bind to antigens presented to them on surface of cells. Foreign particles are taken in and partially digested. Viral antigens are processed and moved to the surface of plasma membrane. Antigen Presenting Cells Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

21 Initiating Immune Response
Macrophages that encounter pathogens lacking proper MHC proteins, or a virus-infected cell with viral proteins stuck to surface, secrete alarm signal. Interleukin-1 Stimulates helper T cells to initiate: Cellular response of T cells Humoral response of B cells Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

22 T Cells: Cellular Response
Helper T cells become activated when they bind to complex of MHC proteins and antigens presented by macrophages. Helper T cells secrete interleukin-2. Stimulates production of cytotoxic T cells. Any cytotoxic T cell whose receptor fits the particular antigen-MHC protein complex begins to multiply rapidly. Any cells bearing traces of viral infection are destroyed. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

23 T Cell Immune Defense Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

24 B Cells: Humoral Response
Recognize invading microbes and mark pathogen for destruction by mechanisms with no “ID check” system of their own. Can bind to free, unprocessed antigens. Antigen particles enter B cells by endocytosis and get processed. Helper T cells that recognize the specific antigen bind to the complex and stimulate B cells to divide. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

25 B Cells: Humoral Response
Antibodies are proteins in class immunoglobulins (Ig)which is subdivided into subclasses based on structure and function. IgM - Secreted during primary response. IgG - Secreted during secondary response. IgD - Receptors for antigens on B cells. IgA - Found in external secretions. IgF - Promotes histamine release. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

26 B Cell Immune Defense Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

27 B Cells: Humoral Response
Plasma cells produce large amounts of particular antibody able to bind to antigen in initial immune response. Memory B cells circulate through lymph and blood waiting for future encounters. Antibody Diversity When antibody is assembled, different DNA sequences are brought together to form composite gene (somatic rearrangement). Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

28 Active Immunity Through Clonal Selection
Binding of antigen to its receptor on the lymphocyte surface stimulates cell division and produces a clone (clonal selection). Primary Immune Response Next time body is invaded by same pathogen, there is a large clone of lymphocytes that can recognize the pathogen. Secondary Immune Response Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

29 The Immune Response Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

30 Triggers immune response without occurrence of infection.
Vaccination Introduction into the body of a disabled pathogen, or a harmless microbe with pathogen proteins displayed on the surface. Triggers immune response without occurrence of infection. Produces circulating memory B cells. May not provide effective future defense if the virus evolves and surface proteins are altered. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

31 Body attacks own tissue. Multiple Sclerosis Type I Diabetes
Immune System Failure Autoimmune Diseases Killer T cells and B cells lose ability to distinguish between self and non-self cells. Body attacks own tissue. Multiple Sclerosis Type I Diabetes Rheumatoid Arthritis Lupus Graves Disease Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

32 Body mounts immune response against harmless substance.
Immune System Failure Allergies Body mounts immune response against harmless substance. Mast cells initiate inflammatory response. Release histamine causing capillaries to swell. Asthma - Histamine causes narrowing of air passages in lungs. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

33 Acquired Immunodeficiency Syndrome first recognized in 1981.
AIDS Acquired Immunodeficiency Syndrome first recognized in 1981. Worldwide, 36.1 million have become infected, and 21.8 million have died. Virus recognizes, attacks, and cripples CD4 T cells. With no defense against infection, any of a variety of otherwise commonplace infections prove fatal. Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

34 Evolution of Immune System Initiating Immune Response
Review First Line of Defense Second Line of Defense Third Line of Defense Evolution of Immune System Initiating Immune Response T Cell Cellular Response B Cell Humoral Response Vaccination Immune System Failure Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies

35 Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies


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