Immune Response and Humoral Immunity
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Questions and Answers

What is the role of B effector/plasma cells in the immune response?

  • To replicate memory cells
  • To destroy pathogen-infected cells
  • To produce antibodies (correct)
  • To stimulate the production of antibodies

    • Where do T cells mature before participating in the immune response?

  • In the thymus gland (correct)
  • In the lymph nodes
  • In the spleen
  • In the bone marrow

    • What characteristic of antibodies ensures their specificity for particular antigens?

  • The constant region's amino acid sequence
  • The variable region's amino acid sequence (correct)
  • The flexibility provided by hinge regions
  • The antibody's disulphide bridges

    • What type of immunity results from the introduction of antibodies from another person or animal?

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

    Which type of cells are involved in stimulating the division of B cells and T killer cells?

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

    What is the primary function of antibodies in the immune response?

    <p>To neutralize toxins released by pathogens</p> Signup and view all the answers

    Which type of immune response involves the destruction of pathogen-infected cells?

    <p>Cell-mediated response</p> Signup and view all the answers

    What structure links the polypeptide chains in antibodies?

    <p>Disulphide bridges</p> Signup and view all the answers

    What role does stomach acid play in the body's defense mechanisms?

    <p>It kills bacteria that enter the digestive system.</p> Signup and view all the answers

    Which of the following is true about phagocytosis?

    <p>It is a process in which white blood cells engulf pathogens.</p> Signup and view all the answers

    What is the primary function of interferons in the body's defense?

    <p>They prevent viruses from spreading to uninfected cells.</p> Signup and view all the answers

    How does the body respond to inflammation?

    <p>By releasing histamines that dilate blood vessels.</p> Signup and view all the answers

    What is the role of lysozyme in the immune response?

    <p>It damages the cell wall of bacteria.</p> Signup and view all the answers

    What is a key difference between bacteria and viruses regarding their cellular structure?

    <p>Bacteria contain membrane-bound organelles, while viruses do not.</p> Signup and view all the answers

    Which of the following statements about HIV is correct?

    <p>HIV leads to AIDS after the immune system is weakened.</p> Signup and view all the answers

    Which pathogen does not require a host to survive?

    <p>Mycobacterium tuberculosis</p> Signup and view all the answers

    What role do tubercles play in tuberculosis infection?

    <p>They prevent the immune system from accessing infected phagocytes.</p> Signup and view all the answers

    Which of the following is a characteristic of viruses?

    <p>They are made up solely of nucleic acid and a protein coat.</p> Signup and view all the answers

    What is a common symptom that occurs after a person becomes HIV positive?

    <p>Persistent fevers and headaches.</p> Signup and view all the answers

    Which feature differentiates bacteria from viruses in terms of their size?

    <p>Bacteria are larger than viruses.</p> Signup and view all the answers

    Which statement is true about the cell components of bacteria?

    <p>Bacteria have a cell membrane and cell wall.</p> Signup and view all the answers

    What is one example of a disease caused by a fungus?

    <p>Black Sigatoka</p> Signup and view all the answers

    What type of pathogen transmission does Malaria involve?

    <p>Vector transmission</p> Signup and view all the answers

    Which of the following is a physical defense mechanism of plants against pathogens?

    <p>Waxy cuticles</p> Signup and view all the answers

    What is necrosis in the context of plant defense?

    <p>Killing of cells near an infection site</p> Signup and view all the answers

    How do terpenoids, such as menthol, help plants defend against pathogens?

    <p>They possess antibacterial properties.</p> Signup and view all the answers

    What role do phenols, such as tannin, play in plant defense?

    <p>Inhibit herbivore digestion</p> Signup and view all the answers

    Which of the following statements about chemical defenses in plants is correct?

    <p>Hydrolytic enzymes break down pathogen cell walls.</p> Signup and view all the answers

    What is the function of callose deposits in plants?

    <p>Strengthen cell walls at injury sites</p> Signup and view all the answers

    What is natural active immunity primarily based on?

    <p>Exposure to an antigen or disease</p> Signup and view all the answers

    What characterizes bactericidal antibiotics?

    <p>They destroy the bacterial cell wall.</p> Signup and view all the answers

    What is the result of the natural selection process in bacteria exposed to antibiotics?

    <p>Some bacteria survive and develop resistance.</p> Signup and view all the answers

    Which statement is true about passive artificial immunity?

    <p>It involves the direct injection of antibodies.</p> Signup and view all the answers

    Which practice helps control the spread of antibiotic-resistant infections in hospitals?

    <p>Isolating patients with infections and screening new admissions.</p> Signup and view all the answers

    What is the main reason for antibiotic resistance in bacteria?

    <p>Overuse and incomplete courses of antibiotics.</p> Signup and view all the answers

    What is the purpose of minimizing selection pressure on bacteria in antibiotic use?

    <p>To reduce the chance of developing resistant strains.</p> Signup and view all the answers

    What is the main function of antibiotics?

    <p>To kill bacteria or stop their growth.</p> Signup and view all the answers

    What is the primary function of stomach acid in the body's defense mechanisms?

    <p>To kill bacteria present in ingested food</p> Signup and view all the answers

    Which process involves the engulfing and destruction of pathogens by white blood cells?

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

    What role do histamines play during inflammation?

    <p>Increase blood flow and vessel permeability</p> Signup and view all the answers

    What distinguishes interferons from other non-specific defenses in the body?

    <p>They prevent virus spread to uninfected cells.</p> Signup and view all the answers

    What occurs after a pathogen is engulfed and destroyed by a phagocyte?

    <p>The phagocyte presents the antigens on its surface.</p> Signup and view all the answers

    What role do cellulose cell walls play in plant defenses against pathogens?

    <p>They provide a physical barrier to pathogen entry.</p> Signup and view all the answers

    Which of the following correctly describes necrosis in plants?

    <p>Cell death occurring near an infection site to contain damage.</p> Signup and view all the answers

    What is the function of callose deposits in plant defenses?

    <p>To block the spread of pathogens through plant tissues.</p> Signup and view all the answers

    How do alkaloids like caffeine contribute to plant defense?

    <p>By deterring herbivores due to their bitter taste.</p> Signup and view all the answers

    Which of the following is NOT a physical defense mechanism in plants?

    <p>Menthol production</p> Signup and view all the answers

    What is the role of terpenoids in plant defenses?

    <p>They possess antibacterial properties.</p> Signup and view all the answers

    In the context of plant defenses, what function do hydrolytic enzymes serve?

    <p>They help break down the cell walls of invading organisms.</p> Signup and view all the answers

    Which of the following is an example of a pathogen that affects plants?

    <p>Tobacco mosaic virus</p> Signup and view all the answers

    What is the primary role of T killer cells in the immune system?

    <p>Destroy cells infected with pathogens</p> Signup and view all the answers

    What is the significance of memory cells in the immune response?

    <p>They replicate rapidly upon re-exposure to the same antigen</p> Signup and view all the answers

    Which component of an antibody is responsible for its specificity to a particular antigen?

    <p>Variable region</p> Signup and view all the answers

    How do antibodies facilitate the destruction of pathogens?

    <p>By binding to pathogens and neutralizing their harmful effects</p> Signup and view all the answers

    What distinguishes active immunity from passive immunity?

    <p>Active immunity results from the body's production of antibodies</p> Signup and view all the answers

    What is the role of T helper cells in the immune response?

    <p>To provide growth factors that stimulate B cells and T killer cells</p> Signup and view all the answers

    Which of the following is NOT a function of antibodies?

    <p>Directly destroying bacterial pathogens</p> Signup and view all the answers

    What structural feature of antibodies contributes to their flexibility for binding to pathogens?

    <p>Hinge region</p> Signup and view all the answers

    What is a key characteristic that differentiates bacteria from viruses?

    <p>Bacteria have organelles while viruses do not.</p> Signup and view all the answers

    Which of the following statements is true regarding the dependency of pathogens on hosts?

    <p>Viruses cannot survive without a host, unlike bacteria.</p> Signup and view all the answers

    What is the initial response of the immune system in tuberculosis infection?

    <p>Tubercles form to seal infected phagocytes.</p> Signup and view all the answers

    What are the main symptoms that appear after a person becomes HIV positive?

    <p>Fever, tiredness, and headaches.</p> Signup and view all the answers

    Which structure is characteristic of bacteria but not found in viruses?

    <p>Cell membrane.</p> Signup and view all the answers

    How does the immune system respond to the presence of tuberculosis bacteria in human lungs?

    <p>It encapsulates infected cells in tubercles.</p> Signup and view all the answers

    Which one of the following accurately describes the size of viruses compared to bacteria?

    <p>Bacteria are significantly larger than viruses.</p> Signup and view all the answers

    What is the outcome when the immune system becomes weakened in a tuberculosis infection?

    <p>Dormant bacteria in tubercles become active.</p> Signup and view all the answers

    What type of immunity is characterized by the presence of antibodies transferred from mother to child?

    <p>Natural passive immunity</p> Signup and view all the answers

    Which process describes the mechanism by which bactericidal antibiotics kill bacteria?

    <p>Destroying the bacterial cell wall</p> Signup and view all the answers

    What is a major consequence of antibiotic-resistant bacteria in healthcare settings?

    <p>Creation of resistant strains</p> Signup and view all the answers

    What method helps minimize the selection pressure on bacteria when using antibiotics?

    <p>Completing the full course of the antibiotic treatment</p> Signup and view all the answers

    What type of immunity is gained through vaccinations?

    <p>Artificial active immunity</p> Signup and view all the answers

    What is the primary action of bacteriostatic antibiotics?

    <p>Inhibiting the growth of bacteria</p> Signup and view all the answers

    Which of the following practices is NOT part of controlling antibiotic-resistant infections in hospitals?

    <p>Disregarding hygiene protocols</p> Signup and view all the answers

    What typically enables bacteria to survive and reproduce despite antibiotic exposure?

    <p>Mutation and natural selection</p> Signup and view all the answers

    Study Notes

    Immune Response

    • The immune response is a complex process that protects the body from pathogens.
    • This response is mediated by lymphocytes, which are produced in the bone marrow.
    • B cells mature in the bone marrow and are responsible for the humoral response.
    • T cells mature in the thymus gland and are involved in the cell-mediated response.
      • T cells are involved in killing infected cells and regulating the immune response.
    • Memory cells are formed during the immune response and remain in the body.
      • They are able to recognize and respond to specific pathogens more quickly upon re-exposure.
    • B effector/plasma cells produce antibodies that target specific antigens on pathogens.
    • T helper cells stimulate B cells and T killer cells to divide and enhance the immune response.
    • T killer cells directly destroy cells infected with pathogens.

    Humoral Response

    • The humoral response is a type of adaptive immunity characterized by the production of antibodies.
    • Antibodies are globular proteins specifically designed to bind to antigens.
    • The binding of antibodies to antigens can neutralize the pathogen.
    • Antibodies consist of four polypeptide chains linked by disulfide bridges.
    • Antibodies have a constant region that interacts with phagocytes to initiate phagocytosis.
    • Antibodies also have a variable region, which differs for each antibody and provides specificity to a particular antigen.
    • Antibody hinge regions provide flexibility for binding to multiple pathogens.

    Cell-Mediated Response

    • The cell-mediated response involves the activation of T cells to directly attack infected cells.
    • T cells identify and destroy cells displaying foreign antigens.
    • Cytotoxic T cells directly kill infected cells.
    • T helper cells play a crucial role in coordinating the immune response.

    Types of Immunity

    • Active immunity develops when the immune system produces antibodies in response to an antigen.
      • Natural active immunity is acquired through exposure to a pathogen.
      • Artificial active immunity is acquired by vaccination.
    • Passive immunity results from the introduction of antibodies from another person or animal.
      • Natural passive immunity is acquired through the transfer of antibodies from mother to fetus through the placenta or breast milk.
      • Artificial passive immunity is acquired through injection of antibodies.

    Pathogens

    • Bacteria are prokaryotic cells that lack a membrane-bound nucleus.
      • They have a cell wall, cell membrane, and cytoplasm.
    • Viruses are much smaller than bacteria and are composed of nucleic acid enclosed in a protein coat.
      • Viruses are obligate intracellular parasites and cannot survive independently.
    • Tuberculosis (TB)
      • Caused by the bacteria Mycobacterium tuberculosis.
      • Infects phagocytes in the lungs, forming tubercles that can become dormant.
      • When the immune system weakens, the bacteria become active and damage lung tissue.
    • Meningitis
      • Can be caused by bacterial infection of the meninges.
    • HIV
      • A viral infection that causes AIDS.
      • Initial symptoms include fever, tiredness, and headaches.
      • Can remain dormant until the weakened immune system leads to AIDS.
    • Influenza
      • A viral infection that infects the ciliated epithelial cells of the respiratory system.
      • Different strains of influenza exist.
    • Athlete's foot
      • A fungal infection spread by direct contact.
    • Malaria
      • A parasitic disease transmitted via a vector (female Anopheles mosquito).

    Plant Defences

    • Plants have evolved physical and chemical defenses against pathogens.
    • Physical barriers include:
      • Cellulose cell walls
      • Lignin layer that thickens cell walls
      • Waxy cuticles.
      • Blocking of old vascular tissue
    • Plant defenses include:
      • Closing of stomata
      • Thickening of cell walls
      • Callose deposits between cell wall and cell membrane
      • Necrosis (cell death)
      • Canker (necrosis of woody tissue)
    • Chemical defences include:
      • Terpenoids (essential oils with antibacterial properties)
      • Phenols (interfere with digestion)
      • Alkaloids (have a bitter flavor)
      • Defensins (cysteine-rich proteins)
      • Hydrolytic enzymes (break down cell walls of invading organisms)

    Primary Non-specific Defences in Animals

    • Physical barriers include:
      • Skin
      • Stomach acid
      • Gut and skin flora
    • Non-specific responses include:
      • Inflammation: Histamines released from mast cells cause vasodilation and increased vascular permeability.
      • Lysozyme: An enzyme found in secretions that breaks down bacterial cell walls.
      • Interferon: Prevents viruses from spreading to uninfected cells.
      • Phagocytosis: White blood cells engulf and destroy pathogens.
      • Blood clotting: Reduces blood loss and prevents entry of pathogens.

    Antibiotics

    • Bactericidal antibiotics kill bacteria by destroying their cell walls.
    • Bacteriostatic antibiotics inhibit bacterial growth by stopping protein synthesis and nucleic acid production.

    Antibiotic Resistance

    • Antibiotic resistance develops through natural selection.
      • Bacteria with resistance genes survive and reproduce.
      • Overuse and misuse of antibiotics contribute to resistance.
    • Hospitals have developed various measures to control antibiotic-resistant infections:
      • Screening of new patients
      • Isolation and treatment of infected patients
      • Judicious use of antibiotics
      • Strict hygiene practices among staff.

    The Immune Response

    • Lymphocytes: Specific immune responses rely on lymphocytes produced in the bone marrow
      • B cells: mature in the bone marrow, responsible for the humoral response, develop into plasma cells and produce antibodies
      • T cells: move from the bone marrow to the thymus gland where they mature, responsible for cell-mediated response
    • Memory Cells: replicate when exposed to a pathogen, remain in the lymph nodes searching for the same antigen, providing a faster immune response
    • B Effector/Plasma Cells: produce antibodies
    • T Helper Cells: stimulate B cells and T killer cells to divide
    • T Killer Cells: destroy pathogen-infected cells

    Humoral Response

    • The antibodies released by plasma cells bind to specific antigens on the surface of pathogens, leading to their neutralization.
    • Neutralization can occur through various mechanisms, including facilitated binding of phagocytes to pathogens, agglutination, and neutralization of toxins.
    • Antibodies are composed of four polypeptide chains, linked by disulfide bridges.
    • They contain a constant region involved in phagocyte interaction and a variable region responsible for their specificity to antigens.
    • Antibodies also have hinge regions, providing flexibility for binding to multiple pathogens.

    Cell-Mediated Response

    • T cells directly destroy infected cells, releasing cytotoxic substances.

    Types of Immunity

    • Active Immunity: Production of antibodies by the immune system in response to an antigen.
      • Natural Active Immunity: Obtained through exposure to an antigen or getting the disease.
      • Artificial Active Immunity: Acquired through vaccinations, stimulating the immune system to produce antibodies.
    • Passive Immunity: Introduction of antibodies from another person or animal.
      • Natural Passive Immunity: Antibodies transferred from mother to fetus through the placenta or breast milk.
      • Artificial Passive Immunity: Antibodies injected into the body.

    Pathogens

    • Bacteria: prokaryotic cells without membrane-bound organelles, containing circular DNA, do not require a host to survive.
      • Examples: Mycobacterium tuberculosis (causes tuberculosis), bacteria responsible for meningitis.
    • Viruses: consist of nucleic acid enclosed in a protein coat, can contain DNA or RNA, entirely dependent on hosts for survival.
      • Examples: HIV (causes AIDS), influenza virus.
    • Other Organisms: Fungi, protozoa, and parasites can also cause disease.
      • Examples: Athlete's foot (caused by fungus), Malaria (caused by a Plasmodium parasite transmitted by mosquitoes)

    Plant Defenses

    • Physical Defenses:
      • Cellulose Cell Walls: provide a strong barrier.
      • Lignin Layer: thickens cell walls.
      • Waxy Cuticles: prevent water loss and pathogen entry.
      • Closing of Stomata: restricts pathogen entry.
      • Callose Deposits: strengthen cell walls.
      • Necrosis: cell death near the infection site.
      • Canker: necrosis of woody tissue.
    • Chemical Defenses:
      • Terpenoids: essential oils with antibacterial properties.
      • Phenols: interfere with digestion, deterring herbivores.
      • Alkaloids: bitter-tasting compounds, discouraging herbivores.
      • Defensins: proteins inhibiting transport channels.
      • Hydrolytic Enzymes: break down pathogen cell walls.

    Primary Non-Specific Defenses in Animals

    • Physical Barriers:
      • Skin: tough, physical barrier made of keratin.
      • Stomach Acid (Hydrochloric Acid): kills bacteria.
      • Gut and Skin Flora: natural bacteria compete with pathogens for resources.
    • Non-Specific Responses:
      • Inflammation: histamine release causes vasodilation, increasing blood flow to the infected area, and blood vessel permeability, allowing immune cells to reach the site.
      • Lysozyme Action: enzyme found in tears and mucus, damages bacterial cell walls.
      • Interferons: prevent viral spread by stopping protein synthesis in viruses.
      • Phagocytosis: white blood cells engulf and destroy pathogens.
      • Blood Clotting: seals wounds, preventing pathogen entry.

    Antibiotics

    • Bactericidal Antibiotics: kill bacteria by destroying their cell walls.
    • Bacteriostatic Antibiotics: inhibit bacterial growth by blocking protein synthesis or nucleic acid production.

    Antibiotic Resistance

    • Bacteria can develop resistance to antibiotics through natural selection.
    • Resistant bacteria survive and reproduce, passing on the resistant allele to their offspring.
    • Strategies to control antibiotic-resistant infections include:
      • Screening patients for infections, isolating infected individuals, and using antibiotics only when necessary.
      • Completing antibiotic courses to ensure complete eradication of bacteria.
      • Handwashing and hygiene protocols to minimize transmission.

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    Description

    Test your knowledge on the immune response and the role of lymphocytes in protecting the body from pathogens. This quiz covers both the humoral and cell-mediated immune responses, including the functions of B cells, T cells, and memory cells. Challenge yourself to recall key concepts relevant to adaptive immunity.

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