Chapter 5: Body's Lines of Defense in Immunology
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Questions and Answers

What is the primary function of the complement system?

  • To attract immune cells to the site of infection
  • To promote inflammation
  • To clear immune complexes from the body
  • To destroy bacteria, cells, and viruses (correct)

    • Which pathway of the complement system is activated by the presence of antigen-antibody complexes?

  • Innate immune system pathway
  • Alternative pathway
  • Classical pathway (correct)
  • Mannan-binding lectin pathway

    • Which of the following is NOT a trigger for the activation of the alternative pathway of the complement system?

  • Lipopolysaccharides (endotoxin) on bacterial cell walls
  • Antibody-antigen complexes (correct)
  • Complex polysaccharides on bacterial cell walls
  • Yeast cell walls

    • What is the role of the C3b fragment in the alternative pathway of the complement system?

    <p>C3b binds to Factor B to form the C3 convertase</p> Signup and view all the answers

    What is the function of the membrane attack complex (MAC) formed by the complement system?

    <p>To lyse target cells by forming a transmembrane channel</p> Signup and view all the answers

    What is the role of properdin (factor P) in the alternative pathway of the complement system?

    <p>Properdin binds to C3b to stabilize the C3 convertase</p> Signup and view all the answers

    How does the mannan-binding lectin (MBL) pathway of the complement system become activated?

    <p>By the binding of MBL to mannose-containing residues on the microbe's glycoproteins</p> Signup and view all the answers

    Which of the following is NOT a function of the complement system?

    <p>Regulation of adaptive immune responses</p> Signup and view all the answers

    How does the alternative pathway of the complement system bypass the need for antigen-antibody interactions?

    <p>By using C3b as a trigger to initiate the pathway</p> Signup and view all the answers

    What is the process called when phagocytes present markers of abnormal self?

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

    How do abnormal host cells decrease their susceptibility to natural killer (NK) cells?

    <p>By decreasing surface MHC Class I molecules</p> Signup and view all the answers

    Which of the following receptors on NK cells detect stress signals on abnormal host cells?

    <p>Toll-like receptors (TLRs) and killer-activating receptors (KARs)</p> Signup and view all the answers

    What is the primary function of type I interferons in the innate immune system?

    <p>To induce cells to activate antiviral defenses</p> Signup and view all the answers

    Which of the following soluble defense mechanisms is responsible for the destruction of microbes?

    <p>Microcidal molecules</p> Signup and view all the answers

    What is the primary function of the complement system in the innate immune response?

    <p>To enhance phagocytosis of microbes</p> Signup and view all the answers

    Which soluble defense mechanism is responsible for the lysis of bacteria?

    <p>Microcidal molecules</p> Signup and view all the answers

    What is the primary function of cytokines and chemokines in the innate immune response?

    <p>To recruit immune cells to the site of infection</p> Signup and view all the answers

    Which of the following statements about the innate immune system is true?

    <p>It relies on pattern recognition receptors to detect molecular patterns associated with pathogens</p> Signup and view all the answers

    Which cellular defense mechanism of the innate immune system involves chemotaxis of leukocytes?

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

    What is the function of cytokines in the immune system?

    <p>Serving as messengers between cells</p> Signup and view all the answers

    Which components lead to the formation of C3 convertase and C5 convertase in the MBL pathway of C activation?

    <p>C3 and C5</p> Signup and view all the answers

    What is the main function of anaphylatoxins in the immune response?

    <p>Activating leukocytes and causing inflammation</p> Signup and view all the answers

    Which cells are involved in the process of phagocytosis in the innate immune system?

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

    What is the role of chemokines in the immune response?

    <p>Attracting leukocytes to infection sites</p> Signup and view all the answers

    Which type of cells are involved in chemotaxis to reach the site of infection?

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

    What is the primary function of PRRs in phagocytosis?

    <p>Recognizing and attaching to pathogens</p> Signup and view all the answers

    What is responsible for engulfing microbes during phagocytosis?

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

    Which molecules are involved in degrading and killing microbes within phagolysosomes?

    <p>Enzymes, oxygen radicals, and nitrous oxide</p> Signup and view all the answers

    How do NK cells detect abnormal host cells?

    <p>By recognizing stress molecules like MICA &amp; MICB</p> Signup and view all the answers

    What initiates inflammation in the innate immune response?

    <p>Attracting &amp; activating phagocytes that secrete cytokines</p> Signup and view all the answers

    Which characteristics are signs of inflammation?

    <p>Pain and heat</p> Signup and view all the answers

    What is the role of phagosomes in phagocytosis?

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

    Which receptors are responsible for binding C3b during phagocytosis?

    <p>Complement receptors</p> Signup and view all the answers

    What happens when phagosomes fuse with lysosomes during phagocytosis?

    <p>Microbes are killed by enzymes and oxygen radicals</p> Signup and view all the answers

    What is the effect of activating the phagocyte during phagocytosis?

    <p>Cytokines &amp; chemokines are secreted to attract other cells involved in the innate immune response</p> Signup and view all the answers

    What is the primary purpose of the Innate Immune System's use of Pattern Recognition Receptors (PRRs)?

    <p>To recognize Pathogen Associated Molecular Patterns (PAMPs) on microbes and initiate the innate immune response</p> Signup and view all the answers

    Which of the following is NOT considered a Pathogen Associated Molecular Pattern (PAMP)?

    <p>Host cell proteins</p> Signup and view all the answers

    What is the primary function of Scavenger Receptors in the innate immune system?

    <p>To internalize bacteria and phagocytose host cells undergoing apoptosis</p> Signup and view all the answers

    What is the role of opsonins in the innate immune response?

    <p>Opsonins enhance the ability of phagocytes to recognize and engulf pathogens.</p> Signup and view all the answers

    Which of the following is NOT a component of the 1st line of defense in the body's immune system?

    <p>Adaptive Immune System</p> Signup and view all the answers

    What is the primary function of Toll-like Receptors (TLRs) in the innate immune system?

    <p>To bind to PAMPs on microbes and initiate the secretion of cytokines from the cell</p> Signup and view all the answers

    What is the main difference between the Innate Immune System and the Adaptive Immune System?

    <p>The Innate Immune System provides a non-specific, immediate response to pathogens, while the Adaptive Immune System provides a specific, delayed response.</p> Signup and view all the answers

    What is the primary purpose of the Adaptive Immune System's recognition of pathogens that have been identified by the Innate Immune System?

    <p>To mount a specific, targeted immune response to the recognized pathogens</p> Signup and view all the answers

    How do host cells avoid being recognized as non-self by the innate immune system?

    <p>Host cells do not have PAMPs, so the immune system can distinguish them from microbes.</p> Signup and view all the answers

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