44 Questions
What is the primary function of the complement system?
To destroy bacteria, cells, and viruses
Which pathway of the complement system is activated by the presence of antigen-antibody complexes?
Classical pathway
Which of the following is NOT a trigger for the activation of the alternative pathway of the complement system?
Antibody-antigen complexes
What is the role of the C3b fragment in the alternative pathway of the complement system?
C3b binds to Factor B to form the C3 convertase
What is the function of the membrane attack complex (MAC) formed by the complement system?
To lyse target cells by forming a transmembrane channel
What is the role of properdin (factor P) in the alternative pathway of the complement system?
Properdin binds to C3b to stabilize the C3 convertase
How does the mannan-binding lectin (MBL) pathway of the complement system become activated?
By the binding of MBL to mannose-containing residues on the microbe's glycoproteins
Which of the following is NOT a function of the complement system?
Regulation of adaptive immune responses
How does the alternative pathway of the complement system bypass the need for antigen-antibody interactions?
By using C3b as a trigger to initiate the pathway
What is the process called when phagocytes present markers of abnormal self?
Opsonization
How do abnormal host cells decrease their susceptibility to natural killer (NK) cells?
By decreasing surface MHC Class I molecules
Which of the following receptors on NK cells detect stress signals on abnormal host cells?
Toll-like receptors (TLRs) and killer-activating receptors (KARs)
What is the primary function of type I interferons in the innate immune system?
To induce cells to activate antiviral defenses
Which of the following soluble defense mechanisms is responsible for the destruction of microbes?
Microcidal molecules
What is the primary function of the complement system in the innate immune response?
To enhance phagocytosis of microbes
Which soluble defense mechanism is responsible for the lysis of bacteria?
Microcidal molecules
What is the primary function of cytokines and chemokines in the innate immune response?
To recruit immune cells to the site of infection
Which of the following statements about the innate immune system is true?
It relies on pattern recognition receptors to detect molecular patterns associated with pathogens
Which cellular defense mechanism of the innate immune system involves chemotaxis of leukocytes?
Phagocytosis
What is the function of cytokines in the immune system?
Serving as messengers between cells
Which components lead to the formation of C3 convertase and C5 convertase in the MBL pathway of C activation?
C3 and C5
What is the main function of anaphylatoxins in the immune response?
Activating leukocytes and causing inflammation
Which cells are involved in the process of phagocytosis in the innate immune system?
Dendritic cells
What is the role of chemokines in the immune response?
Attracting leukocytes to infection sites
Which type of cells are involved in chemotaxis to reach the site of infection?
Neutrophils
What is the primary function of PRRs in phagocytosis?
Recognizing and attaching to pathogens
What is responsible for engulfing microbes during phagocytosis?
Pseudopodia
Which molecules are involved in degrading and killing microbes within phagolysosomes?
Enzymes, oxygen radicals, and nitrous oxide
How do NK cells detect abnormal host cells?
By recognizing stress molecules like MICA & MICB
What initiates inflammation in the innate immune response?
Attracting & activating phagocytes that secrete cytokines
Which characteristics are signs of inflammation?
Pain and heat
What is the role of phagosomes in phagocytosis?
They trap microbes within the phagocyte
Which receptors are responsible for binding C3b during phagocytosis?
Complement receptors
What happens when phagosomes fuse with lysosomes during phagocytosis?
Microbes are killed by enzymes and oxygen radicals
What is the effect of activating the phagocyte during phagocytosis?
Cytokines & chemokines are secreted to attract other cells involved in the innate immune response
What is the primary purpose of the Innate Immune System's use of Pattern Recognition Receptors (PRRs)?
To recognize Pathogen Associated Molecular Patterns (PAMPs) on microbes and initiate the innate immune response
Which of the following is NOT considered a Pathogen Associated Molecular Pattern (PAMP)?
Host cell proteins
What is the primary function of Scavenger Receptors in the innate immune system?
To internalize bacteria and phagocytose host cells undergoing apoptosis
What is the role of opsonins in the innate immune response?
Opsonins enhance the ability of phagocytes to recognize and engulf pathogens.
Which of the following is NOT a component of the 1st line of defense in the body's immune system?
Adaptive Immune System
What is the primary function of Toll-like Receptors (TLRs) in the innate immune system?
To bind to PAMPs on microbes and initiate the secretion of cytokines from the cell
What is the main difference between the Innate Immune System and the Adaptive Immune System?
The Innate Immune System provides a non-specific, immediate response to pathogens, while the Adaptive Immune System provides a specific, delayed response.
What is the primary purpose of the Adaptive Immune System's recognition of pathogens that have been identified by the Innate Immune System?
To mount a specific, targeted immune response to the recognized pathogens
How do host cells avoid being recognized as non-self by the innate immune system?
Host cells do not have PAMPs, so the immune system can distinguish them from microbes.
Explore the concepts of the body's defenses against pathogens, including the 1st line (barriers), 2nd line (innate immune system), and 3rd line (adaptive immune system). Learn about recognition of pathogens, soluble and cellular defenses, inflammation, and the role of Pattern Recognition Receptors in the immune response.
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