Nonspecific Defense Mechanisms Quiz
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Nonspecific Defense Mechanisms Quiz

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Questions and Answers

What is the primary role of the skin in the immune system?

  • To act as a barrier to infection (correct)
  • To promote inflammation
  • To produce antibodies
  • To induce phagocytosis

    • Which of the following is NOT part of the nonspecific immune mechanisms?

  • Antimicrobial proteins
  • Phagocytosis
  • Vaccination (correct)
  • Skin

    • How does the mucous membrane contribute to the immune defense?

  • By secreting protective enzymes (correct)
  • By generating fever
  • By absorbing nutrients
  • By promoting blood circulation

    • What is one function of gingival crevicular fluid in the immune system?

    <p>Washes out non-adherent bacteria</p> Signup and view all the answers

    Which of the following components helps in destroying microbes entering the respiratory system?

    <p>Lysozyme</p> Signup and view all the answers

    What role does keratinization play in the gingival epithelium?

    <p>Provides resistance to trauma</p> Signup and view all the answers

    Which substance is continuously secreted by host cells to counter potential infections?

    <p>Hydrogen peroxide</p> Signup and view all the answers

    What is one of the main interacting mechanisms of the second line of defense in the immune system?

    <p>Inflammatory response</p> Signup and view all the answers

    What percentage of white blood cells do monocytes constitute?

    <p>5%</p> Signup and view all the answers

    What are macrophages primarily known for?

    <p>Engulfing and digesting cellular debris</p> Signup and view all the answers

    Where are fixed macrophages primarily found?

    <p>In lymph nodes and spleen</p> Signup and view all the answers

    What type of immunity is primarily based on the circulation of antibodies?

    <p>Humeral immunity</p> Signup and view all the answers

    What role do neutrophils play in inflammation?

    <p>Controlling periodontal microbiota</p> Signup and view all the answers

    What is indicated by the development of edema and erythema?

    <p>Signs of vascular changes during inflammation</p> Signup and view all the answers

    What substances do anaphylatoxins C3a and C5a stimulate?

    <p>Vascular changes through degranulation</p> Signup and view all the answers

    Chronic inflammatory cells primarily protect the host by:

    <p>Preventing local infection from becoming systemic</p> Signup and view all the answers

    What role do interferons play in the immune response?

    <p>They inhibit virus production in neighboring cells.</p> Signup and view all the answers

    Which of the following statements about complement proteins is true?

    <p>They can opsonize pathogens and assist in lysis.</p> Signup and view all the answers

    What triggers a local inflammatory response?

    <p>Tissue damage releasing histamine.</p> Signup and view all the answers

    What is the main purpose of self-tolerance in the immune system?

    <p>To prevent the body from attacking its own cells.</p> Signup and view all the answers

    Which type of Major Histocompatibility Complex (MHC) is found on all nucleated cells?

    <p>Class I MHC</p> Signup and view all the answers

    What characteristic describes neutrophils in the context of their function?

    <p>They undergo chemotaxis to reach infected tissues.</p> Signup and view all the answers

    What is the life span of neutrophils as they destroy foreign invaders?

    <p>They have an average life span of several days.</p> Signup and view all the answers

    In what way do phagocytes function in the immune system?

    <p>They ingest and destroy invading particles.</p> Signup and view all the answers

    What is the primary role of neutrophils in controlling bacterial infections?

    <p>They are the first leukocytes to arrive and prevent bacterial invasion.</p> Signup and view all the answers

    Which cytokine is expressed by the junctional epithelium to create a chemotactic gradient for neutrophils?

    <p>Interleukin-8 (IL-8)</p> Signup and view all the answers

    What is the consequence of disorders affecting neutrophil chemotaxis?

    <p>Invasive periodontal infection and aggressive periodontitis.</p> Signup and view all the answers

    Which of the following is a function of neutrophils?

    <p>Phagocytosis</p> Signup and view all the answers

    What process involves the coating of bacteria with host proteins to facilitate phagocytosis?

    <p>Opsonization</p> Signup and view all the answers

    Which virulence factor does P.gingivalis produce that affects neutrophil function?

    <p>Periodontain</p> Signup and view all the answers

    How do neutrophils recognize opsonized bacteria?

    <p>Through binding to Fc receptors for complement components</p> Signup and view all the answers

    What is the primary response of the immune system upon contact with bacterial lipopolysaccharides (LPS)?

    <p>Production of interleukins and tumor necrosis factor</p> Signup and view all the answers

    What role do antigen-presenting cells (APCs) play in the immune response within gingival tissues?

    <p>They transport antigens to regional lymph nodes.</p> Signup and view all the answers

    How does scaling and root planing contribute to the immune defense against periodontal pathogens?

    <p>By stimulating antibody production targeting specific microorganisms.</p> Signup and view all the answers

    What is the significance of antibodies specific for P.gingivalis in periodontitis patients?

    <p>They prevent recolonization of deep periodontal pockets.</p> Signup and view all the answers

    What mechanism is impaired in the periodontal pocket compared to a healthy gingival sulcus?

    <p>Oxidative killing mechanisms of neutrophils.</p> Signup and view all the answers

    What is the primary consequence of diminished oxidative killing in periodontal disease progression?

    <p>Enhanced virulence of pathogens.</p> Signup and view all the answers

    What do nonoxidative mechanisms of killing involve in neutrophils?

    <p>Secretion of bactericidal substances into the phagolysosome.</p> Signup and view all the answers

    How does the leukotoxin of A.a. affect phagocytes during an immune response?

    <p>It kills phagocytes, impairing immune function.</p> Signup and view all the answers

    What defines the clinical manifestation of disorders like cyclic neutropenia?

    <p>Reduction in the number of circulating neutrophils.</p> Signup and view all the answers

    Study Notes

    Nonspecific Defense Mechanisms

    • Skin is a physical barrier that's normally impervious to bacteria and viruses, cuts or abrasions can allow pathogens to enter.
    • Mucous Membranes line body cavities and passages, secrete mucus that traps pathogens.
    • Saliva contains several antimicrobial substances:
      • Salivary Peroxidase System
      • Hydrogen Peroxide
      • Lactoferrin
      • Lysozyme
    • Gingival Crevicular Fluid
      • Bathes the gingival sulcus, washing away bacteria and their products.
      • Contains inflammatory mediators, protease inhibitors, and host defense agents.

    Immune Cells

    • Interferons are proteins secreted by virus-infected cells that inhibit neighboring cells from making new viruses.
    • Complement Proteins are involved in both nonspecific and specific defense, initiating inflammation, opsonization, and cell lysis.

    Inflammation

    • Triggered by tissue damage, injured cells release histamine, dilating blood vessels and increasing capillary permeability.
    • This allows phagocytic white blood cells to enter the interstitial fluid.

    Self-Tolerance

    • Lymphocytes bearing antigen receptors mature in the thymus and bone marrow.
    • Lymphocytes with receptors for self molecules are destroyed or inactivated.

    Major Histocompatibility Complex (MHC)

    • Biochemical fingerprint unique to each individual.
    • Class I MHC is found on all nucleated cells.
    • Class II MHC is found on specialized cells of
      the immune system.

    Phagocytosis

    • Ingestion of invading particles by certain white blood cells.
    • Neutrophils: 60-70% of white blood cells, attracted by chemical signals, destroy microbes and often self-destruct in the process.
    • Monocytes mature into macrophages.

    Macrophages

    • Largest phagocytic cells, move through tissues and engulf cellular debris and pathogens.
    • Stimulate lymphocytes and other immune cells to respond to pathogens.
    • Located at strategic points where microbial invasion is likely (e.g., lymph nodes, spleen).

    Humoral and Cell-Mediated Immunity

    • Humoral immunity relies on antibodies circulating in the blood and lymph, defending against extracellular threats.
    • Cell-mediated immunity targets transplanted tissue and cancer cells.

    Inflammation in Response to Bacterial Infection

    • Innate factors, including complement, leukocytes, and mast cells, initiate inflammation by signaling endothelium.
    • Neutrophils control bacteria within the gingival crevice and epithelium.
    • Macrophages and lymphocytes protect the host within the connective tissues, preventing systemic infection.

    Role of Neutrophils in Controlling Bacterial Invasion

    • Neutrophils are the first leukocytes to arrive at the site of inflammation and are the dominant cell type within the junctional epithelium and gingival crevice.
    • Neutrophil functions, including chemotaxis, transepithelial migration, opsonization, phagocytosis, and intracellular killing, must be intact to effectively control bacterial infections.
    • Disorders of neutrophils are linked to invasive periodontal infection and aggressive periodontitis.
    • Neutrophil transepithelial migration depends on a chemotaxin gradient.
    • P. gingivalis can prevent transepithelial migration and inhibit IL-8 secretion.

    Opsonization and Phagocytosis

    • Opsonization: coating bacteria with host proteins to facilitate phagocytosis.
    • IgG isotype facilitates direct phagocytosis by binding to the neutrophil Fc receptor.
    • Antigen-presenting cells (APCs) transport antigen to lymph nodes, promoting IgG antibody production.
    • Scaling and root planing stimulates antibody production against microorganisms like P. gingivalis and A.a.

    Role of Antibodies in Periodontal Health

    • Antibodies facilitate clearance of periodontal pathogens, promoting opsonization and phagocytosis.
    • Neutralize bacterial components involved in colonization and host cell interactions.
    • Antibodies specific to P. gingivalis prevent recolonization of deep periodontal pockets.

    Immune System and Periodontal Disease

    • Periodontal pathogens can evade phagocytic cells as a virulence mechanism (e.g., leukotoxin of A.a.).
    • Specific antibodies to A.a. or antileukotoxin serum protect neutrophils from leukotoxin-mediated injury, enabling phagocytosis.
    • Periodontal manifestations of neutrophil disorders can include:
      • Cyclic neutropenia: reduction in circulating neutrophils.

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    Description

    Test your knowledge on the nonspecific defense mechanisms of the immune system, focusing on physical barriers like skin and mucous membranes, as well as the role of immune cells. This quiz also covers inflammatory responses and the functions of various proteins involved in immunity.

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