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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies How The Animal Body Defends Itself Chapter 25 Copyright © McGraw-Hill.

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Presentation on theme: "Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies How The Animal Body Defends Itself Chapter 25 Copyright © McGraw-Hill."— Presentation transcript:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

27 Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies 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).

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

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

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

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

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

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

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

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


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