Body Defense Mechanisms Quiz
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Questions and Answers

What mechanism does Epstein-Barr Virus (EBV) use to evade the host immune response?

  • Mimicking host proteins
  • Inhibiting interferon signaling
  • Producing a viral homolog of IL-10 (correct)
  • Forming biofilms

    • Which of the following pathogens employs molecular mimicry to evade the immune system?

  • Pseudomonas aeruginosa
  • Hepatitis C Virus
  • Treponema pallidum (correct)
  • Staphylococcus epidermidis

    • How does biofilm formation enhance bacterial resistance to immune responses?

  • By creating a protective extracellular matrix (correct)
  • By contaminating host tissue
  • By mimicking host cells
  • By increasing metabolic activity

    • What is a consequence of HIV targeting Helper T cells?

    <p>Increased susceptibility to secondary infections</p> Signup and view all the answers

    Which pathogen is known for forming biofilms on medical devices?

    <p>Staphylococcus epidermidis</p> Signup and view all the answers

    What is the primary function of Natural Killer (NK) cells?

    <p>To induce programmed cell death in virus-infected cells</p> Signup and view all the answers

    Which component of the complement system is responsible for forming holes in microbial membranes?

    <p>Membrane Attack Complex (MAC)</p> Signup and view all the answers

    What triggers the inflammatory response when tissues are injured?

    <p>Release of histamine from mast cells</p> Signup and view all the answers

    Which type of antibody is primarily responsible for providing long-term immunity?

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

    What role do pyrogens play in the immune response?

    <p>They reset the body's thermostat to induce fever</p> Signup and view all the answers

    Which immune cells are primarily responsible for cell-mediated immunity?

    <p>T cells</p> Signup and view all the answers

    What feature characterizes antigens in the immune system?

    <p>They are foreign molecules recognized by immune cells</p> Signup and view all the answers

    What is one of the main functions of antibodies during an infection?

    <p>Neutralize and clump pathogens for easier clearance</p> Signup and view all the answers

    What is the primary role of the immune system?

    <p>To protect against infection and disease</p> Signup and view all the answers

    Which type of immunity acts as a rapid, non-specific defense?

    <p>Innate Immunity</p> Signup and view all the answers

    What role does desquamation play in the skin's defense mechanism?

    <p>It removes surface microbes</p> Signup and view all the answers

    What is the function of lysozyme in the body's defense system?

    <p>To break down bacterial cell walls</p> Signup and view all the answers

    Which of the following components is categorized under the second line of defense?

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

    How do neutrophils respond to infections?

    <p>By engulfing pathogens and releasing toxins</p> Signup and view all the answers

    What do antimicrobial peptides do?

    <p>Disrupt microbial membranes</p> Signup and view all the answers

    How is phagocytosis primarily carried out by macrophages?

    <p>By engulfing pathogens into a phagosome</p> Signup and view all the answers

    What is the primary function of Helper T Cells (CD4+)?

    <p>Activate B cells and other immune cells</p> Signup and view all the answers

    Which of the following is a role of the lymphatic system in defense?

    <p>Filter lymph fluid and trap pathogens</p> Signup and view all the answers

    What distinguishes autoimmune diseases from other immune system disorders?

    <p>They result from the immune system attacking the body's own cells.</p> Signup and view all the answers

    How do vaccines contribute to the body's immunity?

    <p>They introduce a harmless form of an antigen to produce memory cells.</p> Signup and view all the answers

    What can swollen lymph nodes indicate during an infection?

    <p>Active immune responses</p> Signup and view all the answers

    What is a primary characteristic of immunodeficiency?

    <p>A weakened immune system</p> Signup and view all the answers

    Which of the following is an example of a hypersensitivity reaction?

    <p>Allergies to pollen</p> Signup and view all the answers

    What is herd immunity?

    <p>A state where a significant portion of a population is immune to a disease.</p> Signup and view all the answers

    What is the main purpose of antigenic variation in pathogens?

    <p>To change surface proteins to avoid immune detection</p> Signup and view all the answers

    Which pathogen is known for changing its surface glycoproteins to evade the immune response?

    <p>Trypanosoma brucei</p> Signup and view all the answers

    How does Mycobacterium tuberculosis avoid being destroyed by the immune system?

    <p>By residing in macrophages and preventing lysosome fusion</p> Signup and view all the answers

    What mechanism does Streptococcus pneumoniae use to inhibit phagocytosis?

    <p>Having a thick polysaccharide capsule</p> Signup and view all the answers

    What is a strategy that HIV employs to evade the immune system?

    <p>Utilizing host proteins to avoid complement-mediated destruction</p> Signup and view all the answers

    What factor inhibits the complement system to facilitate immune evasion?

    <p>Surface molecules that bind complement regulatory proteins</p> Signup and view all the answers

    Which of the following is NOT a method used by pathogens to evade the immune response?

    <p>Immediate replication in blood plasma</p> Signup and view all the answers

    What is one way that Herpes Simplex Virus (HSV) evades the immune system?

    <p>Hiding in nerve cells during latent infections</p> Signup and view all the answers

    Study Notes

    Body Defense Mechanisms

    • The immune system is the body's network of cells, tissues, and organs protecting against infection and disease. It defends against bacteria, viruses, fungi, and parasites.

    • The immune system has two components:

      • Innate immunity: a rapid, non-specific first response.
      • Adaptive immunity: a slower, more specific response with memory for future encounters with pathogens.

    First Line of Defense

    • Physical barriers:

      • Skin: The largest organ, composed of tightly packed epithelial cells. Sebum and sweat contain antimicrobial substances. Dead skin cell shedding removes surface microbes.
      • Mucous Membranes: Line respiratory, gastrointestinal, and urogenital tracts. Mucus traps pathogens, and cilia moves trapped particles out of the body.

    • Chemical Defenses:

      • Stomach Acid: Kills ingested pathogens.
      • Lysozyme: An enzyme, found in tears, saliva, sweat that breaks down bacterial cell walls.
      • Antimicrobial Peptides: Short proteins (like defensins) that disrupt microbial membranes.
      • Flushing mechanisms: Tears, urine, and mucus wash away microbes. Example: blinking.

    Second Line of Defense: Innate Immunity

    • Phagocytes:

      • Macrophages: Reside in tissues; engulf pathogens by phagocytosis, and release cytokines to recruit more immune cells.
      • Neutrophils: Most abundant white blood cells, rapidly recruited to infection sites. They engulf pathogens, release enzymes, and toxic substances.
      • Mechanism of Phagocytosis: Pathogens are engulfed into a phagosome, fuses with a lysosome, and enzymes degrade the pathogen.

    • Natural Killer (NK) Cells: Recognize and destroy cells lacking self-markers (MHC class I molecules). Typically virus-infected or cancerous cells. Release perforins and granzymes that induce apoptosis.

    • Inflammatory Response:

      • Tissues injured release histamine.
        • Blood vessels dilate causing redness and heat, allowing more immune cells to the area.
        • Blood vessels become more permeable, causing swelling.
      • Purpose: speeds up healing process and recruits immune cells to fight infection.
      • Clinical Example: Swelling and redness around a cut is inflammation.

    • Fever: Pyrogens (substances) reset the body's thermostat in the hypothalamus to inhibit microbial growth and enhance immune response.

    • Complement system: A set of about 30 proteins that work together to destroy microbes by punching holes in microbial membranes (Membrane Attack Complex - MAC). Enhances phagocytosis through opsonization, making pathogens easier for phagocytes to identify.

    • Interferons: Released by virus-infected cells to warn neighboring cells, stimulating them to produce antiviral proteins.

    Third Line of Defense: Adaptive Immunity

    • Antigen Recognition: Foreign molecules (proteins, polysaccharides) recognized by the adaptive immune system.
    • B Cells and Antibodies: B cells mature in the bone marrow and, upon antigen activation, differentiate into plasma cells that secrete antibodies, which provide long-term immunity.
    • Types of immunoglobulins include IgG (most common), IgA (found in mucous secretions), and IgM (first antibody made).
    • T Cells: Mature in the thymus, crucial for cell-mediated immunity; including helper T cells (CD4+) and cytotoxic T cells (CD8+).
    • Helper T cells: Activate B cells and other immune cells.
    • Cytotoxic T cells: Kill infected or abnormal cells.
    • Memory cells: Responsible for faster response upon re-exposure to the same pathogens.

    Role of the Lymphatic System

    • Lymph nodes: Filter lymph fluid and trap pathogens.
    • Spleen: Filters blood, removing old red blood cells and pathogens.
    • Lymphatic vessels: Transport lymph fluid, carrying immune cells and waste products away from tissues.

    Immune System Disorders

    • Autoimmune diseases: The immune system mistakenly attacks the body's own cells (Examples: Multiple sclerosis, type 1 diabetes).
    • Allergies: Hypersensitivity to non-harmful antigens, triggering an exaggerated immune response.
    • Immunodeficiency: Primary (genetic) or secondary (acquired) conditions where the immune system is weakened, e.g., HIV/AIDS.

    Vaccination and Immune Memory

    • Vaccines: Introduce a harmless form of an antigen to the body, allowing it to produce memory cells without causing disease; useful against certain diseases.

    • Herd immunity: A significant portion of a population that's immune to a disease prevents its spread to unvaccinated individuals.

    Pathogen Evasion Mechanisms

    • Antigenic variation: Pathogens change their surface proteins to escape immune cell recognition. Examples: Influenza virus, Trypanosoma brucei (sleeping sickness).
    • Hiding in host cells: Pathogens hide within host cells to avoid immune detection. Examples: Mycobacterium tuberculosis, Herpes simplex virus.
    • Inhibiting phagocytosis: Pathogens produce factors to prevent phagocytes from engulfing and destroying them. Examples: Streptococcus pneumoniae.
    • Inhibiting complement system: The pathogen produces factors to inhibit the complement system.
    • Disrupting cytokine signaling: Some pathogens interfere with the host's immune communication system.
    • Molecular mimicry: Some pathogens produce molecules mimicking host proteins, blending in to avoid detection.
    • Biofilm formation: Microorganisms form communities of cells shielded by a protective extracellular matrix, making them resistant to immune responses.

    Clinical Examples

    • Swollen lymph nodes during an infection: Indicates active immune response.

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    Related Documents

    Body Defense Mechanisms Lecture 2 PDF

    Description

    Test your knowledge on the immune system and its functions! This quiz covers the two components of immunity, physical barriers, and chemical defenses that protect the body against pathogens. Explore how the body defends itself from infections and diseases.

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