Gram-Negative Bacteria and Their Effects on the Human Gut
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Questions and Answers

What is the primary role of Gram-negative bacteria fimbriae in the intestinal tract?

  • Promoting colonization by alien microbes
  • Binding to glycoproteins on epithelial cells (correct)
  • Secreting vitamins for the host
  • Boosting the activity of immunological tissues

    • How do bacteria in the human GI tract primarily contribute to nutrition and digestion?

  • Breaking down complex carbohydrates into simple sugars (correct)
  • Producing enzymes that aid in nutrient absorption
  • Supplying essential amino acids for protein synthesis
  • Generating energy through metabolic processes

    • What is the main impact of alterations in the GI flora due to poor nutrition or antibiotic use?

  • Improved digestion and nutrient absorption
  • Increased risk of colonization by nonresident microbes (correct)
  • Decreased likelihood of colon cancer
  • Enhanced resistance to gastrointestinal diseases

    • Which statement accurately reflects the role of some bacteria in the colon like Bacteroides?

    <p>Their metabolites contribute to carcinogenesis</p> Signup and view all the answers

    What is the significance of bacterial flora in protecting their host from alien microbe infections?

    <p>Supporting the development of immunological tissues</p> Signup and view all the answers

    How do bacteria in the human GI tract help prevent gastrointestinal diseases?

    <p>By guarding against colonization by harmful microbes</p> Signup and view all the answers

    What temperature should raw seafood be held at according to the text?

    <p>Below 4°C</p> Signup and view all the answers

    Which group of people is highly susceptible to virulent Listeria?

    <p>Pregnant women and the elderly</p> Signup and view all the answers

    What is the mortality rate of immune compromised individuals, newborns, or very young individuals due to Listeria infection?

    <p>Approximately 30%</p> Signup and view all the answers

    Which is the most pathogenic species causing listeriosis in humans?

    <p>Listeria monocytogenes</p> Signup and view all the answers

    In what temperature range should cooked seafood be held according to the text?

    <p>Below 4°C or above 60°C</p> Signup and view all the answers

    What can happen following invasion of macrophages by virulent strains of Listeria?

    <p>Multiplication resulting in disruption of cells and septicemia</p> Signup and view all the answers

    What is the main characteristic of innate immunity?

    <p>It is nonspecific in nature</p> Signup and view all the answers

    Which of the following is a physical component of skin defense?

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

    What is the role of dendritic cells in skin defense?

    <p>Phagocytize pathogens</p> Signup and view all the answers

    How does sebum contribute to skin defense?

    <p>Keeps skin pliable and less likely to break or tear</p> Signup and view all the answers

    Which of the following is a function of perspiration in skin defense?

    <p>Inhibits pathogen growth by drawing water from their cells</p> Signup and view all the answers

    Why are epithelial cells lining body cavities considered a part of the immune defense?

    <p>They are living and provide a barrier</p> Signup and view all the answers

    What is a commensal relationship?

    <p>A relationship where there is no apparent benefit or harm to either organism</p> Signup and view all the answers

    Which bacterium is mentioned as the best known for associating with humans?

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

    Why do specific bacteria colonize specific tissues according to the text?

    <p>Because host tissues provide essential nutrients and growth factors for the bacterium</p> Signup and view all the answers

    What characterizes tissue specificity of normal bacterial flora?

    <p>It is usually due to properties of both the host and the bacterium</p> Signup and view all the answers

    Why is E.coli considered a commensal bacterium even though it may have parasitic or mutualistic characteristics?

    <p>Because it is well-studied and known to colonize the human intestinal tract</p> Signup and view all the answers

    What explains tissue tropism in bacteria according to the text?

    <p>Host tissues provide essential nutrients and growth factors for the bacterium</p> Signup and view all the answers

    What is the role of opsonins in the immune response?

    <p>Identify antigens for phagocytes</p> Signup and view all the answers

    Which part of the immune system is responsible for screening tissues of the body for foreign antigens?

    <p>Lymphatic system</p> Signup and view all the answers

    What is the composition of lymph, as mentioned in the text?

    <p>Similar to blood plasma</p> Signup and view all the answers

    Which cells recognize and attack foreign antigens present in lymph nodes?

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

    What is the function of antibodies in neutralizing toxins?

    <p>Neutralize toxins</p> Signup and view all the answers

    From where are lymphocytes produced in the body?

    <p>Red bone marrow</p> Signup and view all the answers

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