Microbiology Chapter 10 - Host-Microbe Interactions
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Questions and Answers

What is one of the primary benefits provided by our normal microbiota?

  • Manufacturing hormones
  • Destroying pathogens
  • Producing toxic substances
  • Manufacturing vitamins (correct)

    • Which of the following differentiates a pathogen from a normal microbiota?

  • Pathogens are always present in the human body.
  • Pathogens can cause disease. (correct)
  • Normal microbiota can cause disease.
  • Pathogens help in vitamin synthesis.

    • What does dysbiosis describe?

  • Pathogen resistance
  • A diverse microbial community
  • Microbiota disruption (correct)
  • A stable microbiota environment

    • Can a member of the normal microbiota ever act as a pathogen? Which example illustrates this?

    <p>Group B streptococci causing infections in newborns</p> Signup and view all the answers

    What is the term for the preference of a pathogen for a specific host or tissue?

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

    Which term describes the ability of a microbe to cause disease?

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

    How do virulence factors primarily harm the host?

    <p>By directly damaging host cells and provoking immune responses</p> Signup and view all the answers

    What does the basic reproduction number (R0) indicate?

    <p>Pathogen transmissibility or contagiousness</p> Signup and view all the answers

    Which type of immune response is primarily mediated by T cells?

    <p>Cellular response</p> Signup and view all the answers

    What is the role of haptens in the immune system?

    <p>Require linkage to a larger molecule for immune activation</p> Signup and view all the answers

    Which set of cells are primarily responsible for presenting antigens to T cells?

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

    Which T cell type is primarily involved in coordinating the adaptive immune response?

    <p>T helper 1 cells</p> Signup and view all the answers

    What process is responsible for the large diversity of T cell and B cell receptors?

    <p>Gene rearrangement</p> Signup and view all the answers

    Where do T cells mature after being produced in the bone marrow?

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

    What is the primary function of T regulatory cells?

    <p>Regulate the functions of other immune cells</p> Signup and view all the answers

    Which class of MHC is found on all body cells?

    <p>MHC I</p> Signup and view all the answers

    Which immune response involves antibody production by B cells?

    <p>Humoral response</p> Signup and view all the answers

    What happens to T and B cells that fail the self-tolerance test?

    <p>They undergo apoptosis</p> Signup and view all the answers

    What distinguishes MHC II from MHC I in terms of the type of antigens they present?

    <p>MHC II presents intracellular antigens</p> Signup and view all the answers

    Which of the following T cell types directly destroys infected or cancerous cells?

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

    What are the stages of the cellular adaptive immune response?

    <p>Antigen presentation and lymphocyte activation</p> Signup and view all the answers

    What defines BSL-2+ agents?

    <p>Dangerous, incurable agents that are not vaccine preventable</p> Signup and view all the answers

    Which type of immunity is characterized by generalized responses and is nonspecific?

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

    Which of the following is NOT part of BSL-3 biosafety measures?

    <p>Treatment of agents with vaccines</p> Signup and view all the answers

    What is the primary function of the lymphatic system?

    <p>Filtering and circulating fluid in the body</p> Signup and view all the answers

    Which process is essential for the detection of pathogens in the lymphatic system?

    <p>Fluid circulation and screening</p> Signup and view all the answers

    What best describes granulocytes?

    <p>They contain granules that are visible when stained</p> Signup and view all the answers

    What is the significance of defensins among antimicrobial peptides?

    <p>They target and disrupt the plasma membrane of pathogens</p> Signup and view all the answers

    Which of the following examples is a barrier defense in innate immunity?

    <p>Presence of epithelial tissue</p> Signup and view all the answers

    What role does the hygiene hypothesis relate to immune responses?

    <p>Increased microbial diversity strengthens immune health</p> Signup and view all the answers

    What common characteristic do macrophages, neutrophils, and dendritic cells share?

    <p>All are primarily involved in phagocytosis</p> Signup and view all the answers

    What triggers leukocytosis in a patient’s blood sample?

    <p>Infection causing rapid leukocyte production</p> Signup and view all the answers

    Which of these describes noncritical equipment usage in healthcare settings?

    <p>Dedicated for single-patient use</p> Signup and view all the answers

    What is a hallmark feature of adaptive immunity?

    <p>Ability to exhibit memory after exposure</p> Signup and view all the answers

    What is the role of molecular factors in the second line of defense?

    <p>Recruiting other leukocytes and restricting pathogen growth</p> Signup and view all the answers

    What characterizes an attenuated pathogen?

    <p>It remains infectious but has reduced virulence.</p> Signup and view all the answers

    What does ID50 represent in the context of infectious diseases?

    <p>The infectious dose needed to infect 50% of exposed hosts.</p> Signup and view all the answers

    Which of the following is true regarding endotoxins?

    <p>Endotoxins originate from lipid A of Gram-negative bacteria.</p> Signup and view all the answers

    What is the most common portal of entry for pathogens in humans?

    <p>Respiratory mucous membranes.</p> Signup and view all the answers

    Which type of immune cell is primarily responsible for presenting antigens to T cells?

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

    How does antigenic masking help pathogens evade the host immune system?

    <p>By disguising itself with host molecules.</p> Signup and view all the answers

    What is the function of chemokines in the immune response?

    <p>Attract white blood cells to specific locations</p> Signup and view all the answers

    What are siderophores used for by pathogens?

    <p>To snatch iron from transferrin for survival.</p> Signup and view all the answers

    Which pathway of complement activation is triggered by the presence of antibodies?

    <p>Classical complement cascade</p> Signup and view all the answers

    What are the four cardinal signs of inflammation?

    <p>Redness, pain, localized heat, swelling</p> Signup and view all the answers

    What is one of the main effects of Type I exotoxins?

    <p>They bind to receptors and alter gene expression.</p> Signup and view all the answers

    What is a cytokine storm?

    <p>An exaggerated cytokine response</p> Signup and view all the answers

    Which statement about LD50 is accurate?

    <p>LD50 measures the amount of toxin required to kill 50% of hosts.</p> Signup and view all the answers

    What role do siderophores play in the context of pathogens?

    <p>They help pull iron from iron-binding proteins</p> Signup and view all the answers

    Which method do pathogens use to block phagocytosis?

    <p>By forming protective capsules.</p> Signup and view all the answers

    Which type of cells are involved in innate immunity and directly target viruses and tumors?

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

    What are the five steps to infection starting from entering the host?

    <p>Enter, adhere, invade, replicate, transmit.</p> Signup and view all the answers

    What physiological changes occur during the vascular changes phase of inflammation?

    <p>Vasodilation and increased vessel permeability</p> Signup and view all the answers

    What is a key characteristic of cytocidal effects of bacterial and viral pathogens?

    <p>They can lead to cell death or damage.</p> Signup and view all the answers

    Which of the following is NOT a way pathogens gain entry into the host?

    <p>By passing through the epidermis.</p> Signup and view all the answers

    What effect does fever have on the immune response?

    <p>Increases the efficiency of phagocytes</p> Signup and view all the answers

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

    <p>Bind to and neutralize specific antigens</p> Signup and view all the answers

    How do invasin factors function in helping pathogens invade host tissues?

    <p>They break down host tissues and induce uptake of the pathogen.</p> Signup and view all the answers

    What describes the role of exotoxins in bacterial infections?

    <p>They can induce toxic shock and immune suppression.</p> Signup and view all the answers

    What characterizes chronic inflammation?

    <p>Exacerbation of tissue injury</p> Signup and view all the answers

    What is the role of angiogenesis in inflammation?

    <p>To build new blood vessels during healing</p> Signup and view all the answers

    What distinguishes a superantigen from a regular antigen?

    <p>It activates a large number of T cells non-specifically</p> Signup and view all the answers

    What mechanism do hemolytic bacteria use to acquire iron from the host?

    <p>Breaking down red blood cells</p> Signup and view all the answers

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

    <p>They activate other immune cells and provide support.</p> Signup and view all the answers

    What type of activation is required for T cell-independent B cell activation?

    <p>Involves cross-linking of B cell receptors by non-protein antigen epitopes.</p> Signup and view all the answers

    Which of the following correctly describes T cell activation?

    <p>It requires primary and secondary signals including MHC interaction and co-stimulatory proteins.</p> Signup and view all the answers

    What limits T cell-independent activated B cells?

    <p>They lead to a lack of affinity maturation.</p> Signup and view all the answers

    What occurs during T cell clonal expansion?

    <p>T cells proliferate and differentiate into effector and memory cells.</p> Signup and view all the answers

    Which cells are involved in the killing of infected or cancerous cells?

    <p>Cytotoxic T cells, which use perforins and granzymes.</p> Signup and view all the answers

    What is immunological memory?

    <p>The capacity to generate a stronger and faster immune response upon re-exposure to the same pathogen.</p> Signup and view all the answers

    What are the two main cytokine classes associated with T helper responses?

    <p>TH1, which promotes T cytotoxic cell activation, and TH2, which promotes B cell maturation.</p> Signup and view all the answers

    Which type of antibodies is produced first during a primary immune response?

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

    What is the main purpose of serological testing?

    <p>To measure a patient's antibody response to determine past exposure or vaccination status.</p> Signup and view all the answers

    What distinguishes memory B cells from effector B cells?

    <p>Memory B cells remain in the body for a longer duration and provide faster responses upon re-exposure.</p> Signup and view all the answers

    How do antibodies facilitate the immune response?

    <p>They neutralize pathogens and enhance phagocytosis through opsonization.</p> Signup and view all the answers

    Which antibody isotype is most abundant in human blood?

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

    What does convalescent plasma contain, and how is it used?

    <p>It contains antibodies from recovered patients and is used to provide passive immunity to current patients.</p> Signup and view all the answers

    What role does normal microbiota play in relation to potential pathogens?

    <p>They help in manufacturing vitamins and compete with potential pathogens.</p> Signup and view all the answers

    How can dysbiosis directly affect the host?

    <p>By allowing opportunistic pathogens to flourish and cause disease.</p> Signup and view all the answers

    What distinguishes the terms pathogenicity and virulence?

    <p>Pathogenicity describes the ability to cause disease while virulence describes the extent of that disease.</p> Signup and view all the answers

    What can cause a harmless species of normal microbiota to become a pathogen?

    <p>Disruption of normal microbiota leading to opportunistic infection.</p> Signup and view all the answers

    Which of the following best describes how virulence factors operate?

    <p>They enable pathogens to adhere to and invade host tissues.</p> Signup and view all the answers

    What is one way pathogens may evolve new virulence factors?

    <p>By undergoing random mutations and natural selection.</p> Signup and view all the answers

    What does the effective reproduction number (Re) of a pathogen indicate?

    <p>The actual number of secondary infections generated by an infected individual.</p> Signup and view all the answers

    How does tropism influence the emergence of new pathogens?

    <p>It shapes the host and tissue range that pathogens can infect.</p> Signup and view all the answers

    What is the definition of ID50?

    <p>The number of pathogens required to cause an infection in 50% of hosts</p> Signup and view all the answers

    What role do adhesins play in the infection process?

    <p>They are used by pathogens to adhere to host tissues.</p> Signup and view all the answers

    Which type of exotoxin is known to bind to host cell receptors and alter gene expression?

    <p>Type I exotoxins</p> Signup and view all the answers

    Which strategy do pathogens use to avoid the immune system through antigenic variation?

    <p>They periodically alter their surface molecules.</p> Signup and view all the answers

    What is a significant characteristic of endotoxins?

    <p>They can cause toxic shock.</p> Signup and view all the answers

    Which process describes the ability of a pathogen to exist quietly inside a host?

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

    What do siderophores do in the context of bacterial pathogens?

    <p>They snatch iron from host proteins.</p> Signup and view all the answers

    Which of the following is a common portal of entry for pathogens in humans?

    <p>Skin abrasions</p> Signup and view all the answers

    What distinguishes Type II exotoxins from other types of exotoxins?

    <p>They cause lysis of host cells.</p> Signup and view all the answers

    How do pathogens commonly exit the host they are infecting?

    <p>Via the same route used as their portal of entry</p> Signup and view all the answers

    What is the function of lipases in the context of bacterial pathogens?

    <p>To break down lipids for nutrient acquisition</p> Signup and view all the answers

    Which immune response is primarily responsible for activating B cells to produce antibodies?

    <p>Humoral response</p> Signup and view all the answers

    What is the primary effect of Type III exotoxins?

    <p>They block protein synthesis.</p> Signup and view all the answers

    What is the primary role of dendritic cells in the adaptive immune response?

    <p>Acting as antigen-presenting cells</p> Signup and view all the answers

    Which of the following is a common method pathogens use to evade phagocytosis?

    <p>Utilizing toxins to kill phagocytes</p> Signup and view all the answers

    What types of antigens do T cytotoxic cells primarily respond to?

    <p>Intracellular antigens</p> Signup and view all the answers

    What is a distinguishing feature of a pathogen's effective reproductive number (Re)?

    <p>It varies based on host-pathogen interactions.</p> Signup and view all the answers

    Which of the following describes the function of T helper 1 cells?

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

    Where do B cells mature after their production in the bone marrow?

    <p>Bone marrow</p> Signup and view all the answers

    What is the role of chemokines in the immune response?

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

    Which type of cytotoxic immune cell directly destroys infected or cancerous cells?

    <p>Natural Killer (NK) cells</p> Signup and view all the answers

    What is the role of major histocompatibility complex (MHC) proteins?

    <p>Present antigens to T cells for recognition</p> Signup and view all the answers

    What does a cytokine storm refer to?

    <p>An exaggerated cytokine response</p> Signup and view all the answers

    Which type of T cell has CD8+ receptors and interacts with MHC I molecules?

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

    What is the process called when T and B cells that fail the self-tolerance test are eliminated?

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

    What is the primary function of interleukins in the immune system?

    <p>Enhance inflammation and activate immune responses</p> Signup and view all the answers

    What type of proteins are primarily involved in presenting antigens to T cells?

    <p>MHC proteins</p> Signup and view all the answers

    During which stage of adaptive immune activation do lymphocytes release cytokines?

    <p>Lymphocyte activation</p> Signup and view all the answers

    Which type of cell is primarily responsible for processing and presenting extracellular antigens?

    <p>Antigen-presenting cells (APCs)</p> Signup and view all the answers

    During which phase of inflammation does vasodilation and increased blood vessel permeability occur?

    <p>Vascular changes phase</p> Signup and view all the answers

    How do iron-binding proteins function in the immune response?

    <p>They help maintain iron levels crucial for oxygen delivery</p> Signup and view all the answers

    What is the main function of T regulatory cells in the immune response?

    <p>Suppress immune responses to maintain homeostasis</p> Signup and view all the answers

    What mechanism allows pathogens like hemolytic bacteria to obtain iron from host tissues?

    <p>Breaking down red blood cells</p> Signup and view all the answers

    What mainly accounts for the diversity of T cell and B cell receptors?

    <p>Somatic recombination of gene segments</p> Signup and view all the answers

    What is the role of macrophages in the immune system?

    <p>They act as phagocytes and antigen-presenting cells.</p> Signup and view all the answers

    Which type of antigen is presented by MHC I molecules?

    <p>Intracellular antigens</p> Signup and view all the answers

    Which strategy do some pathogens use to overcome iron-binding proteins?

    <p>Producing siderophores</p> Signup and view all the answers

    What is the primary effect of T helper 2 cells in the immune response?

    <p>Promote B cell antibody production</p> Signup and view all the answers

    What is the main purpose of the complement system in the immune response?

    <p>Boost immune defenses against invaders</p> Signup and view all the answers

    Which column of the complement activation pathways is triggered by antibodies?

    <p>Classical complement cascade</p> Signup and view all the answers

    What is a superantigen?

    <p>A highly immunogenic toxin that activates many T cells</p> Signup and view all the answers

    What distinguishes BSL-2 agents from BSL-1 agents?

    <p>BSL-2 agents are not vaccine preventable.</p> Signup and view all the answers

    Which statement about first-line defenses in the immune system is correct?

    <p>They are designed to prevent pathogen entry.</p> Signup and view all the answers

    How do antimicrobial peptides (AMPs) function to combat pathogens?

    <p>They disrupt pathogen membranes and stimulate leukocytes.</p> Signup and view all the answers

    What role does the lymphatic system play in immune responses?

    <p>It filters lymph and detects pathogens.</p> Signup and view all the answers

    What distinguishes granulocytes from agranulocytes?

    <p>Granulocytes contain granules that can be seen when stained.</p> Signup and view all the answers

    What is a significant characteristic of BSL-4 agents?

    <p>They have no known cures or treatments.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of adaptive immunity?

    <p>It includes barriers like skin and mucous membranes.</p> Signup and view all the answers

    In healthcare settings, what is a primary goal of transmission precautions?

    <p>To reduce direct contact with patients.</p> Signup and view all the answers

    What does leukocytosis refer to?

    <p>An increase in white blood cells.</p> Signup and view all the answers

    Which of the following represents the role of macrophages in the immune system?

    <p>Presenting antigens to T cells.</p> Signup and view all the answers

    What type of pathogen is associated with BSL-2+ agents?

    <p>Dangerous and incurable with no vaccines.</p> Signup and view all the answers

    One major function of molecular factors in the immune system is to:

    <p>Recruit other leukocytes to infection sites.</p> Signup and view all the answers

    What does the hygiene hypothesis propose regarding normal microbiota?

    <p>Decreased diversity negatively affects immune responses.</p> Signup and view all the answers

    What primary benefit do T helper cells provide to the adaptive immune system?

    <p>They enhance the activation of other immune cells.</p> Signup and view all the answers

    What is a limitation of T cell-independent activated B cells?

    <p>They lack the ability to form memory B cells.</p> Signup and view all the answers

    What two signals are necessary for T cell activation?

    <p>T cell receptor interaction with MHC-antigen and co-stimulatory proteins.</p> Signup and view all the answers

    How do T cytotoxic cells induce death in infected or cancerous cells?

    <p>By using perforins to lyse the target membrane.</p> Signup and view all the answers

    What happens to B cells upon encountering their specific antigen?

    <p>They differentiate into plasma cells and memory B cells.</p> Signup and view all the answers

    What defines the primary immune response compared to the secondary immune response?

    <p>The primary response generates IgM first and then IgG.</p> Signup and view all the answers

    What role do antibodies play in the immune response?

    <p>They tag antigens for phagocytosis and neutralize toxins.</p> Signup and view all the answers

    Which antibody isotype is produced early during an infection?

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

    What characterizes immunological memory?

    <p>The generation of memory cells that enable rapid reactivation of the immune response.</p> Signup and view all the answers

    What is serological testing primarily used for?

    <p>To assess a patient's antibody titers to determine exposure to a disease.</p> Signup and view all the answers

    What is the role of co-stimulatory proteins in B cell activation?

    <p>They provide necessary signals to complete B cell activation.</p> Signup and view all the answers

    What is a characteristic feature of T cell clonal expansion?

    <p>T cells multiply and differentiate based on cytokine signals.</p> Signup and view all the answers

    What distinguishes T cell-dependent B cell activation from T cell-independent activation?

    <p>T cell-dependent B cell activation requires cytokines released by T helper cells.</p> Signup and view all the answers

    What role do normal microbiota play in the immune system?

    <p>They manufacture vitamins, compete with pathogens, and promote immune system maturation.</p> Signup and view all the answers

    What condition can arise from the overgrowth of normally present microbes due to antibiotics?

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

    What term describes the specific mechanisms pathogens use to evade host defenses?

    <p>Virulence factors</p> Signup and view all the answers

    How can a microbe that is normally harmless in one host become pathogenic in another?

    <p>Due to differences in host immunity and microbiota composition</p> Signup and view all the answers

    What does tropism refer to in the context of pathogens?

    <p>The preference of a pathogen for a specific host or tissue</p> Signup and view all the answers

    What does a high virulence factor indicate about a pathogen?

    <p>It typically causes severe disease</p> Signup and view all the answers

    What is the effective reproduction number (Re) of a pathogen?

    <p>A measure of the average number of secondary cases produced by one infected individual in a population</p> Signup and view all the answers

    What is the basic reproduction number (R0) used to measure?

    <p>The transmissibility of a pathogen</p> Signup and view all the answers

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

    <p>To provide help and support to other immune cells</p> Signup and view all the answers

    What is the main limitation of T cell-independent activation of B cells?

    <p>It has limited capacity for memory formation</p> Signup and view all the answers

    Which of the following describes the signals required for T cell activation?

    <p>Primary and secondary signals involving receptor interactions</p> Signup and view all the answers

    What determines the differentiation of T cells during clonal expansion?

    <p>Cytokines released from other immune cells</p> Signup and view all the answers

    How do T cytotoxic cells induce apoptosis in target cells?

    <p>By releasing granzymes and perforins</p> Signup and view all the answers

    What is the primary action of antibodies secreted by plasma cells?

    <p>They enhance phagocytosis and neutralize toxins</p> Signup and view all the answers

    Which type of antibody is primarily present at the initial stages of an infection?

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

    What is convalescent plasma therapy used for?

    <p>To provide passive immunity to newly infected individuals</p> Signup and view all the answers

    How does the antibody isotype profile change between primary and secondary immune responses?

    <p>Secondary responses produce a higher concentration of IgG with limited IgM</p> Signup and view all the answers

    What are the characteristics of effector B cells?

    <p>They differentiate into plasma cells that secrete antibodies</p> Signup and view all the answers

    What type of antigen do T-independent B cells primarily respond to?

    <p>Repetitive non-protein polysaccharide epitopes</p> Signup and view all the answers

    Which immune cells are primarily responsible for initiating the adaptive immune response?

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

    How do fever-inducing pyrogens enhance the immune response?

    <p>By acting on the hypothalamus.</p> Signup and view all the answers

    Which type of cytokines specifically attract white blood cells to areas of infection?

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

    What occurs during the resolution phase of inflammation?

    <p>White blood cells undergo apoptosis.</p> Signup and view all the answers

    What does the term ID50 refer to in infectious diseases?

    <p>The number of virions needed to infect 50% of exposed hosts</p> Signup and view all the answers

    Which statement correctly describes exotoxins?

    <p>They are soluble proteins that can cause cytopathic effects.</p> Signup and view all the answers

    Which pathway of complement activation is triggered without the involvement of antibodies?

    <p>Alternative pathway</p> Signup and view all the answers

    What is a primary role of siderophores in pathogen defense mechanisms?

    <p>Exploiting iron-binding proteins.</p> Signup and view all the answers

    What is a common method by which pathogens evade the immune system?

    <p>Altering surface antigens periodically.</p> Signup and view all the answers

    Which type of pathogen is most likely to cause septic shock?

    <p>Endotoxins from E. coli</p> Signup and view all the answers

    What characterizes a cytokine storm?

    <p>Exaggerated immune response.</p> Signup and view all the answers

    What type of immune cells are classified as natural killer (NK) cells?

    <p>Innate immune cells</p> Signup and view all the answers

    Which of the following is NOT a step in the infection process?

    <p>Invading host immune cells</p> Signup and view all the answers

    What is the primary constituents of pus formed in response to a wound?

    <p>Dead tissue cells and bacteria.</p> Signup and view all the answers

    What role do siderophores play for pathogens?

    <p>They bind and sequester iron from the host.</p> Signup and view all the answers

    Type II exotoxins primarily affect which part of the host cell?

    <p>Plasma membrane</p> Signup and view all the answers

    Which immune response is specifically characterized by the production of antibodies?

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

    What is the primary difference between T cytotoxic cells and T helper cells?

    <p>T cytotoxic cells destroy infected cells, whereas T helper cells coordinate the immune response.</p> Signup and view all the answers

    Which of the following represents a common portal of exit for pathogens?

    <p>Respiratory droplets</p> Signup and view all the answers

    What describes the role of eicosanoids in the inflammatory process?

    <p>Act as signaling molecules to mediate inflammation.</p> Signup and view all the answers

    What is a key characteristic of attenuated pathogens?

    <p>They maintain infectious potential but are weakened.</p> Signup and view all the answers

    What is the impact of NSAIDs on inflammation?

    <p>Inhibit mediators of inflammation.</p> Signup and view all the answers

    What role do haptens play in the immune system?

    <p>They need to be linked to proteins or polysaccharides to stimulate an immune response.</p> Signup and view all the answers

    What is the general function of interferons in the immune response?

    <p>Signal the presence of pathogens.</p> Signup and view all the answers

    How can pathogens induce cytopathic effects in host cells?

    <p>By releasing toxins and disrupting normal cell functions.</p> Signup and view all the answers

    Which type of MHC molecule presents extracellular antigens?

    <p>MHC II</p> Signup and view all the answers

    Which of the following is an example of antigenic mimicry?

    <p>A capsule resembling host carbohydrates.</p> Signup and view all the answers

    Why do T and B cells that fail the self-tolerance test undergo apoptosis?

    <p>To eliminate the risk of autoimmune reactions.</p> Signup and view all the answers

    During which stage of adaptive immune response do activated T and B cells proliferate?

    <p>Lymphocyte proliferation and differentiation</p> Signup and view all the answers

    What is a common function of adhesins in pathogens?

    <p>To facilitate attachment to host cells.</p> Signup and view all the answers

    What can happen to LD50 values depending on circumstances?

    <p>They can decrease based on route of exposure.</p> Signup and view all the answers

    What is the function of T regulatory cells?

    <p>They control the functions of other immune cells.</p> Signup and view all the answers

    Which type of antigen receptors do both T cells and B cells possess?

    <p>Antigen recognition receptors</p> Signup and view all the answers

    What occurs in the thymus during T cell maturation?

    <p>T cells are tested for self-MHC recognition.</p> Signup and view all the answers

    How are antigens that are processed for MHC I presentation primarily derived?

    <p>From intracellular pathogens.</p> Signup and view all the answers

    What distinguishes T helper 1 cells from T helper 2 cells in terms of their function?

    <p>T helper 1 cells activate macrophages and cytotoxic T cells, whereas T helper 2 cells stimulate B cells to produce antibodies.</p> Signup and view all the answers

    What initiates the cellular and humoral responses to eliminate an antigen?

    <p>Lymphocyte activation and cytokine release.</p> Signup and view all the answers

    What classes of MHC molecules interact with the different CD receptors on T cells?

    <p>CD4 interacts with MHC II, and CD8 interacts with MHC I.</p> Signup and view all the answers

    Which of the following best describes the relationship between T cell receptors (TCRs) and the diversity of antigen recognition?

    <p>TCRs can recognize a vast variety of antigens due to the large number of T cells produced.</p> Signup and view all the answers

    Which biosafety level consists of agents that pose limited risk?

    <p>BSL-1</p> Signup and view all the answers

    In which biological structure do B cells mature?

    <p>Bone marrow</p> Signup and view all the answers

    Which of the following is NOT a characteristic of BSL-3 agents?

    <p>Contain highly effective vaccines</p> Signup and view all the answers

    What is a characteristic of innate immunity?

    <p>Generalized responses</p> Signup and view all the answers

    What function does the lymphatic system serve?

    <p>Screen and filter body fluid for pathogens</p> Signup and view all the answers

    Which of the following correctly describes first-line defenses in the immune system?

    <p>Physical and chemical barriers preventing entry</p> Signup and view all the answers

    What distinguishes BSL-4 agents from those of lower biosafety levels?

    <p>Have no cures or treatments available</p> Signup and view all the answers

    What is the primary function of antimicrobial peptides like defensins?

    <p>To destroy a broad range of pathogens</p> Signup and view all the answers

    What may swollen lymph nodes indicate?

    <p>Presence of foreign pathogens or invaders</p> Signup and view all the answers

    What role do mechanical barriers play in the innate immune system?

    <p>Physically block pathogen entry into the body</p> Signup and view all the answers

    What is leukocytosis?

    <p>Increase in leukocyte levels in the blood</p> Signup and view all the answers

    What defines barrier defenses in the context of innate immunity?

    <p>Physical, chemical, and mechanical strategies</p> Signup and view all the answers

    Which of the following correctly describes granulocytes?

    <p>Contain visible granules when stained</p> Signup and view all the answers

    What is the primary purpose of transmission precautions in healthcare?

    <p>To prevent specific disease transmissions</p> Signup and view all the answers

    How does normal microbiota influence immune responses?

    <p>By fine-tuning immune responses to pathogens</p> Signup and view all the answers

    Study Notes

    Chapter 10 - Host-Microbe Interaction and Pathogenesis

    • Normal Microbiota Benefits: Manufacture vitamins, compete with pathogens, and mature the immune system
    • Normal Microbiota vs. Pathogen: Pathogens cause disease; normal microbiota colonize various body sites (skin, digestive, genital, etc.) and aren't typically disease-causing.
    • Dysbiosis: Microbiota disruption, e.g., antibiotics killing normal gut microbiota, allowing Clostridioides difficile to overgrow.
    • Normal Microbiota as Pathogens: A harmless microbe in one host can be pathogenic in another (e.g., Group B Streptococcus causing neonatal infections).
    • Tropism: Pathogen preference for a specific host and/or tissue. Emerging pathogens often expand tropism to infect humans.
    • Pathogenicity, Virulence, Virulence Factors:
    • Pathogenicity: Ability to cause disease.
    • Virulence: Degree of disease caused.
    • Virulence factors: Mechanisms enabling pathogens to evade our defenses (adherence, invasion, etc.).
    • Virulence Factor Damage: Directly damage host cells or provoke a harmful immune response.
    • Reproduction Numbers (R0 & Re):
    • R0: Measurable transmissibility (e.g., R0=2, one infected person infects 2 others).
    • Re: More appropriate in epidemics/pandemics, as host-pathogen interactions change.
    • Attenuated Pathogens: Infectious but weakened pathogens; created by growing in cell culture, losing virulence factors, and no longer causing disease in immunocompetent hosts. Used in vaccines.
    • ID50 & LD50:
    • ID50: Infectious dose killing 50% of hosts. Lower ID50 = more infectious pathogen
    • LD50: Lethal dose killing 50% of hosts; values influenced by species, host immunity, exposure route (can change).
    • Toxins (Endo- & Exo-):
    • Toxins: Molecules harming the host.
    • Endotoxins: Lipid A component of Gram-negative LPS; lower LD50; can cause septic shock (e.g., E. coli).
    • Exotoxins: Soluble proteins; Gram-positive and -negative bacteria produce them.
    • Type I: Bind via receptors, alter host gene expression (e.g., superantigens & TSS).
    • Type II: Damage cell membranes, cause cell lysis (e.g., hemolysins).
    • Type III: Intracellular toxins, enter cells (e.g., diphtheria, pertussis, cholera, botulinum toxins).

    Chapter 10 - Host-Microbe Interaction and Pathogenesis (cont.)

    • Infection Steps: Enter host, adhere to tissues, invade/obtain nutrients, replicate/avoid immune, transmit to new host.
    • Portal of Entry: Site pathogen enters. Most common is mucous membranes (respiratory).
    • Adhesins: Virulence factors promoting attachment to host cells (cell wall components, capsules, fimbriae, pili).
    • Biofilms & Adhesion: Adhesins create biofilms; common sites are implanted devices and organs.
    • Invasins & Motility: Invasins enable tissue/cell invasion (extracellular enzymes breaking down tissues, causing blood clotting), flagella for motility.
    • Siderophores: Molecules scavenging iron from host proteins.
    • Lipases & Proteases: Enzymes breaking down lipids and proteins during tissue invasion.

    Chapter 11 - Innate Immunity

    • Immune System Branches: Innate (generalized, non-specific) and adaptive (specific, slower, memory).
    • Lines of Defense: Barrier, cellular/molecular, and adaptive defenses.
    • Microbiota & Immune Response: Normal microbiota fine-tune the immune system to fight pathogens and differentiate between pathogens vs. nonpathogens (Hygiene Hypothesis).
    • First-Line Defenses: Prevent pathogen entry (mechanical, chemical, physical).
    • Mechanical: Rinse/flush pathogens, mucociliary escalator.
    • Chemical: Attack invaders/limit growth (e.g., lysozyme, HCl, fatty acids).
    • Physical: Block entry (epithelial tissue, skin).
    • Antimicrobial Peptides (AMPs): Destroy pathogens, stimulate leukocytes, disrupt membranes/cell walls. Defensins are a class of AMPs.
    • Lymphatic System: Collects, circulates, filters fluid.
    • Primary lymphoid tissues: Thymus and bone marrow (leukocyte production/maturation).
    • Secondary lymphoid tissues: Lymph nodes, spleen, MALT (filter lymph).
    • Lymph: Fluid screened for pathogens.
    • Granulocytes & Agranulocytes:
    • Granulocytes: Neutrophils, eosinophils, basophils, mast cells (contain granules).
    • Agranulocytes: Monocytes, dendritic cells, lymphocytes (lack granules).
    • Differential WBC Count: Identifies leukocyte imbalances that can indicate infection.
    • Leukocytosis: Elevated WBC count.
    • Molecular Factors (Second Line): Recruit leukocytes, restrict pathogen growth, trigger fever, stimulate inflammation.

    Chapter 11 - Innate Immunity (cont.)

    • Phagocytic Cells: Macrophages, neutrophils, dendritic cells. Dendritic cells most efficient APC for T cells activation.
    • Lymphocytes Categories: NK (innate), T Cells (adaptive), B cells (adaptive).
    • Cytokines: Signaling proteins for cell communication; include interleukins [ILs], tumor necrosis factor (TNF), interferons (IFNs). Chemokines attract WBCs.
    • Cytokine Storm: Exaggerated cytokine response.
    • Iron-Binding Proteins: Combat pathogens by limiting iron availability. Some pathogens overcome this by using siderophores or hemolysins

    Chapter 11 - Innate Immunity (cont. 2)

    • Complement System: Cascade of proteins boosting immune defenses. Three pathways (classical, alternative, lectin). Regulation important to prevent damage to host cells.
    • Inflammation Stages:
    • Vascular changes: Vasodilation, increased permeability, exudate accumulation.
    • Leukocyte recruitment: Chemoattractants recruit more WBCs.
    • Resolution/resolution phase: Inflammation decreases, damaged tissues repair.

    Chapter 11 - Innate Immunity (cont. 3)

    • Fever: Abnormally high body temperature.
    • Pyrogens trigger fever acting on the hypothalamus.
    • Promotes fighting infection/repair (enhancing interferons, phagocytes, leukocytes production, limiting pathogen growth).

    Chapter 12 - Adaptive Immunity - (Part of a Continuing Topic Block)

    • Antigen, Epitope, and Antigen-Binding Proteins: Antigens are foreign molecules; epitopes are antigen parts recognized; antibodies bind to these. Protein/polysaccharide antigens are most immunogenic.
    • Hapten & Superantigen: Incomplete antigens requiring carriers; potent T helper cell activators, respectively.
    • Adaptive Immunity Types:
    • Cellular: T cell-mediated.
    • Humoral: Antibody-mediated (B-cell based).
    • Adaptive Immunity Stages:
    • Antigen presentation
    • Lymphocyte activation
    • Lymphocyte proliferation and differentiation
    • Antigen elimination and memory
    • T & B Cell Origins and Maturation:
    • T cells: Bone marrow made, thymus matured (cellular, humoral).
    • B cells: Bone marrow made, bone marrow matured (humoral).

    Chapter 12 - Adaptive Immunity (cont.)

    • T Cell Lineages & Roles:
    • T cytotoxic cells (CD8+): Destroy infected/cancer cells (MHC I). T Helper cells (CD4+): Coordinate adaptive immunity (MHC II).
    • T Regulatory Cells: Control other immune cell functions to limit or end immune responses.
    • Antigen Recognition Diversity: Numerous T and B cells generated to recognize a broad range of antigens.
    • Self-Tolerance Mechanisms: Elimination of T and B cells reacting with “self” to prevent autoimmune disorders; T-cell selection in the thymus. (more detailed in the text)
    • MHC Proteins: "Self-proteins" presenting antigens to T cells.
    • MHC I: On all cells; presents intracellular antigens to T cytotoxic cells.
    • MHC II: On APCs; presents extracellular antigens to T helper cells.
    • Cellular Adaptive Immune Response Stages: (detailed in original text).
    • Antigen Processing (MHC I vs. MHC II): (detailed explanation).

    Chapter 12 - Adaptive Immunity (cont.)

    • Role of TH Cells: Crucial for activating almost all aspects of adaptive immunity.
    • TH1: Activate Tc and macrophages for intracellular pathogen destruction, cellular response.
    • TH2: Activate B cells, driving antibody production.
    • T-cell-independent Activation of B cells: Specific case bypasses TH cell involvement
    • Antibody Structure & Function: Proteins secreted by plasma cells; similar to B cell receptor; several isotypes including IgG, IgM. Neutralize pathogens, participate in complement activation, and increase phagocytosis (detailed in text). (more details).
    • Types of Humoral Immunity: (detailed categories).

    Chapter 12 - Adaptive Immunity (cont.)

    • Immunological Memory: Rapid and effective response to previously encountered pathogens. Memory cells (B and T) responsible.
    • Isotype Profile Changes (Primary vs. Secondary Responses): Shift occurs in response type after re-exposure with a rapid and targeted IgG increase during the secondary response.
    • Serological Testing: Assess antibody titers; can diagnose exposure to a disease. (additional detail).
    • Convalescent Plasma: Provides passive immunity using antibodies from someone recovering, treatment.

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    Explore the critical concepts in Chapter 10 focusing on host-microbe interactions and pathogenesis. Understand the roles of normal microbiota, the impact of dysbiosis, and the mechanisms by which pathogens can cause diseases. This quiz covers pathogenicity, virulence factors, and the interplay between beneficial and harmful microbes.

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