The 3 Lines of Immune Defense
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Questions and Answers

What is the primary function of the first line defenses?

  • To recognize and neutralize pathogens
  • To adapt to different types of infections
  • To enhance immune responses
  • To block entry of a microbe (correct)

    • Which of the following is NOT a physical first line defense?

  • Lysozyme (correct)
  • Intact Skin
  • Cough reflex
  • Mucous Coat

    • Why do burn patients have a high risk of infection?

  • They produce more bodily fluids
  • They have increased microbial resistance
  • Their immune response is heightened
  • They lose intact skin as a barrier (correct)

    • What role do cilia play in the first line defenses?

    <p>They trap and expel microbes</p> Signup and view all the answers

    Which substance is primarily responsible for breaking down bacterial cell walls?

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

    How does the outward flow of liquids function as a defense mechanism?

    <p>It physically sweeps away microbes</p> Signup and view all the answers

    Which reflex is part of the physical first line defenses?

    <p>Sneezing reflex</p> Signup and view all the answers

    Which of the following best describes the first line defenses?

    <p>Non-specific and always active</p> Signup and view all the answers

    What is the significance of tears in the body’s first line defenses?

    <p>They contain high levels of lysozyme</p> Signup and view all the answers

    Which of the following is a feature of first line defenses?

    <p>They are always present and provide constant protection</p> Signup and view all the answers

    What role do acids play in the body's defense against pathogens?

    <p>They create an acidic environment that inhibits pathogen growth.</p> Signup and view all the answers

    Which of the following is NOT part of the second line of defense?

    <p>T Helper Lymphocytes</p> Signup and view all the answers

    What is a primary function of neutrophils in the immune system?

    <p>Engulf and destroy pathogens</p> Signup and view all the answers

    What are memory cells responsible for in the immune system?

    <p>Recognizing and responding to previously encountered pathogens</p> Signup and view all the answers

    Which statement about the complement system proteins is true?

    <p>They enhance immune response and can destroy pathogens.</p> Signup and view all the answers

    Which of the following is a characteristic sign of inflammation?

    <p>Swelling due to fluid accumulation</p> Signup and view all the answers

    What is one function of interferons during viral infections?

    <p>Warn neighboring cells to increase their defenses</p> Signup and view all the answers

    What is the primary role of B Lymphocytes in the immune system?

    <p>To produce antibodies</p> Signup and view all the answers

    Which of the following best describes the role of T Helper lymphocytes?

    <p>They activate the specific immune response.</p> Signup and view all the answers

    Which immune response is activated when a pathogen breaches the first and second lines of defense?

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

    Match the following physical first line defenses with their descriptions:

    <p>Intact Skin = Blocks entry of microbes through a physical barrier Outward Flow of Liquids = Expels microbes through liquids like sweat and saliva Hairs and Cilia = Trap and expel particles and microbes from the respiratory tract Reflexes = Expel microbes through actions like coughing and sneezing</p> Signup and view all the answers

    Match the following chemical first line defenses with their functions:

    <p>Lysozyme = Breaks down peptidoglycan in bacteria Saliva = Contains enzymes that prevent microbial growth Tears = Protects the eyes by breaking down bacteria Sweat = Contains substances that inhibit microbial growth</p> Signup and view all the answers

    Match the following examples of microbial defense with their corresponding categories:

    <p>Intact Skin = Physical defense Cough Reflex = Physical defense Lysozyme in Tears = Chemical defense Mucous Coat = Physical defense</p> Signup and view all the answers

    Match the following descriptions of first line defenses to their correct types:

    <p>Chemical Defense = Works to weaken or destroy pathogens Physical Defense = Provides a barrier to pathogen entry Intact Skin = A primary example of physical defense Lysozyme = An enzyme functioning in chemical defense</p> Signup and view all the answers

    Match the following bodily secretions with their defensive properties:

    <p>Tears = High lysozyme concentration Urine = Flows outward to prevent entry of microbes Saliva = Contains enzymes to inhibit bacteria Sweat = Helps to wash away potential pathogens</p> Signup and view all the answers

    Match the following defenses with their outcomes:

    <p>Cough Reflex = Expels unwanted microbes from the respiratory tract Hairs in the Nose = Traps particles and microbes Mucous Coat = Catches smaller microbes and debris Intact Skin = Prevents microbial entry</p> Signup and view all the answers

    Match the following functions with their respective defenses:

    <p>Reflex Actions = Immediate expulsion of microbes Skin Barrier = Forms a protective layer Outward Flow of Liquids = Physically removes microbes Chemical Enzymes = Inhibit bacterial growth</p> Signup and view all the answers

    Match the following components of the first line defenses with their characteristics:

    <p>Mucous = Thick fluid trapping microbes Cilia = Assist in moving trapped debris out Reflexes = Involuntary actions preventing infection Skin Keratin = Strengthens the barrier against pathogens</p> Signup and view all the answers

    Match the following biological barriers with the specific threats they block:

    <p>Intact Skin = Blocks most microbial entry Hairs and Mucous = Trap larger and smaller particles respectively Chemical Enzymes = Attacks bacterial structure Tears = Protects the eyes from infection</p> Signup and view all the answers

    Match the immune system components to their respective functions:

    <p>Phagocytosis = Engulf and destroy pathogens Complement system proteins = Enhance immune response and destroy pathogens T Helper Lymphocytes = Activate specific immune response Antibodies = Bind to and neutralize pathogens</p> Signup and view all the answers

    Match the signs of inflammation with their descriptions:

    <p>Redness = Dilation of blood vessels Heat = Increased blood flow Swelling = Accumulation of fluid in tissue Pain = Sensitivity due to tissue damage</p> Signup and view all the answers

    Match the type of immune cell with its action:

    <p>Neutrophils = Attack bacteria non-specifically Cytotoxic T Lymphocytes = Kill infected self-cells B Lymphocytes = Produce antibodies Memory cells = Recognize past infections for faster response</p> Signup and view all the answers

    Match the mechanisms of the second line of defense with their functions:

    <p>Inflammatory response = Prevents infection spread and calls reinforcements Fever = Speeds up immune response and inhibits pathogen growth Interferons = Warn neighboring cells during infections Phagocytosis = Removes harmful organisms</p> Signup and view all the answers

    Match the term with the correct definition:

    <p>Acquired immunity = The body’s specific and strongest immune response Antimicrobial chemicals = Substances that inhibit the growth of pathogens First line defenses = Physical and chemical barriers against pathogens Second line defenses = Internal responses to pathogens that breach initial barriers</p> Signup and view all the answers

    Match the immune cell type with its role in adaptive immunity:

    <p>T Lymphocytes = Responsible for cell-mediated immunity B Lymphocytes = Generate antibodies against pathogens Memory B cells = Ensure quick response to previously encountered pathogens T Helper cells = Support and activate other immune cells</p> Signup and view all the answers

    Match the immune system components with their roles:

    <p>Cytokines = Signaling molecules that mediate immune responses Natural killer cells = Target and kill viral-infected cells Macrophages = Engulf and digest cellular debris and pathogens Dendritic cells = Present antigens to T cells</p> Signup and view all the answers

    Match the protein roles with their functions:

    <p>Interferons = Protect surrounding cells during viral infections Complement proteins = Lyse pathogens and promote inflammation Cytokines = Regulate immune responses and cell communication Antibodies = Neutralize and mark pathogens for destruction</p> Signup and view all the answers

    Match the statement with the defense mechanism it refers to:

    <p>Macrophages that engulf pathogens = Phagocytosis Presence of acids in sweat = Chemical barrier Increased body temperature during infection = Fever Expansion of blood vessels during injury = Inflammatory response</p> Signup and view all the answers

    What percentage of white blood cells do neutrophils constitute?

    <p>60%</p> Signup and view all the answers

    What process do neutrophils use to navigate to the site of inflammation?

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

    What happens to neutrophils after they digest bacteria?

    <p>They die shortly after.</p> Signup and view all the answers

    What visible sign can result from the high casualties suffered by neutrophils during an infection?

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

    How do neutrophils enter the tissue from the bloodstream?

    <p>By migrating through endothelial cells</p> Signup and view all the answers

    Study Notes

    First Line Defenses

    • Definition: Prevent microbes from entering the body.
    • Characteristics: Non-specific; always function the same way.
    • Types:
      • Physical:
        • Intact skin acts as a barrier.
        • Outward flow of liquids (sweat, urine, mucus) prevents microbial entry.
        • Hairs, mucous coat, and cilia trap microbes in the respiratory tract.
        • Reflexes (cough, sneeze, vomit, blink) expel microbes.
      • Chemical:
        • Lysozyme breaks down peptidoglycan to prevent bacterial infections.
        • Acids (sweat, stomach, vagina) create hostile environments for pathogens.
        • Antimicrobial chemicals are secreted by various glands and tissues, including semen.

    Second Line Defenses

    • Definition: Cells, tissues, and organs that protect the body from pathogens.
    • Components:
      • Phagocytosis: White blood cells (WBCs) engulf and destroy pathogens.
        • Neutrophils are an example of WBCs that can engulf bacteria.
      • Inflammatory response:
        • Triggered by tissue injury.
        • Signs: redness, heat, swelling, pain.
      • Complement system proteins: Enhance the immune response and directly destroy pathogens.
      • Interferons: Proteins that warn neighboring cells of viral infections.
      • Fever: Speeds up the immune response and inhibits pathogen growth.

    Third Line Defenses

    • Definition: Adaptive or acquired immunity; the body's most specific and strongest response to infection.
    • Components:
      • T Lymphocytes:
        • T Helper Lymphocytes: Activate a specific immune response.
        • Cytotoxic T Lymphocytes: Kill infected cells to prevent pathogen spread.
      • B Lymphocytes: Produce antibodies.
      • Memory cells: B and T cells that remain after infection to quickly recognize and respond to the pathogen if it returns.
      • Antibodies: Target and neutralize pathogens or alert WBCs for destruction.

    First Line Defenses

    • Physical barriers block entry of microbes

      • Intact skin acts as a physical barrier, preventing microbes from entering the body
        • The keratin layer on the skin effectively blocks most microbes
        • Burn patients are at high risk of infection due to the loss of the skin barrier
      • Outward flow of liquids from body openings, such as sweat, urine, saliva, and mucous, acts as a physical barrier against microbes
      • Respiratory tract defenses include hairs, mucous, and cilia:
        • Hairs trap large particles, while mucous traps smaller microbes and debris
        • Cilia beat constantly to move mucous out of the nose and mouth
      • Reflexes, including coughing, sneezing, vomiting, and blinking, expel microbes that attempt to enter the body

    • Chemical defenses prevent microbial entry

      • Lysozyme, an enzyme found in body secretions (tears, saliva, sweat, semen, cervical secretions), breaks down peptidoglycan, preventing bacterial infections
      • Acids in body tissues (sweat, stomach acid, vaginal lactic acid) create an environment unfavorable for pathogens
      • Antimicrobial chemicals, such as those found in semen, protect against microbes

    Second Line Defenses

    • Phagocytosis: White blood cells (WBCs) engulf and destroy pathogens

      • Neutrophils are a type of WBC that targets bacteria in a non-specific manner
      • Phagocytes act generally and cannot target specific pathogens or launch an immune response

    • Inflammatory response: The body's way to prevent infection spread, remove damaged tissue, and call for immune reinforcements

      • Occurs when an area of the body is injured, leading to:
        • Redness (due to blood vessel dilation in the area)
        • Heat (due to increased blood flow)
        • Swelling (due to fluid accumulating in tissue)
        • Pain (due to tissue damage, swelling, and chemical mediators that increase nerve sensitivity)

    • Complement system proteins: Enhance the immune response and directly destroy pathogens

    • Interferons: Proteins that warn neighboring cells of viral infection, protecting them

    • Fever: Speeds up the immune response of WBCs and B cell antibody production

      • May inhibit pathogen growth and division

    Third Line Defenses

    • Adaptive or Acquired Immunity: The body's most specific and powerful defense against infection
      • Occurs when microbes bypass first and second line defenses
      • Depends on T and B lymphocytes to target and destroy specific pathogens
    • T Helper Lymphocytes activate specific immune response
    • Cytotoxic T Lymphocytes kill infected self-cells to prevent pathogen spread
    • B Lymphocytes produce antibodies and can activate T Helper cells
    • Memory cells (B and T cells) remain after infection, allowing the body to recognize and respond rapidly to subsequent exposures to the same pathogen
    • Antibodies target and bind to pathogens to neutralize them or alert WBCs for destruction

    Second and Third Line Defenses

    • Second and Third line defenses are internal defenses
      • They work together to fight against pathogens that successfully bypass first line defenses
      • Make up the body's immune system, essential for fighting infection and disease

    Neutrophils; The First Responders

    • Neutrophils are the most abundant type of white blood cell, accounting for 60% of our total white blood cell count.
    • They are the primary responders to bacterial and fungal infections.
    • Neutrophils are phagocytic cells, meaning they engulf and destroy foreign invaders like bacteria.
    • Neutrophils navigate to the site of infection through a process called chemotaxis, following chemical signals released by damaged cells and pathogens.
    • Neutrophils are short-lived cells, unable to renew their cellular structures. They die after engulfing a limited number of bacteria.
    • The accumulation of dead neutrophils and other cellular debris forms pus at the site of infection or injury.

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    Description

    Explore the first and second line defenses of the immune system. Learn how physical barriers and various immune responses protect the body from pathogens through both non-specific and specific mechanisms. Test your understanding of the components involved in these critical defense strategies.

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