4th exam part 2
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What does susceptibility refer to in the context of host-pathogen interactions?

  • The overall health of the host
  • A lack of resistance to a disease (correct)
  • The ability to resist disease
  • The body's response to a specific pathogen

    • Which type of immunity is characterized by a response to a specific pathogen?

  • Passive immunity
  • Adaptive immunity (correct)
  • Non-specific resistance
  • Innate immunity

    • What role do physical barriers, such as skin, play in the immune system?

  • They create an acidic environment to deter microbes.
  • They produce cytokines to recruit immune cells.
  • They provide antibodies to fight pathogens.
  • They serve as the primary barrier to pathogen entry. (correct)

    • Which of the following is NOT considered a first line of defense in the immune system?

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

    What is the function of the ciliary escalator in the respiratory tract?

    <p>To transport trapped microbes away from the lungs</p> Signup and view all the answers

    Which component is NOT part of the innate immune system?

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

    What is microbial antagonism?

    <p>The competition between different microbes</p> Signup and view all the answers

    What characteristic makes skin an effective barrier against pathogens?

    <p>It is composed of many layers of keratinized cells.</p> Signup and view all the answers

    Which is the most visible physical barrier of the innate immune system?

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

    Which factor is NOT known to affect non-specific resistance?

    <p>Genetic predisposition</p> Signup and view all the answers

    What is the role of normal microbiota in protecting the host?

    <p>Occupying niches that pathogens might occupy</p> Signup and view all the answers

    What type of symbiotic relationship is characterized by one organism benefiting while the other is unaffected?

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

    Which of the following describes opportunistic pathogens?

    <p>Infect individuals with compromised immune systems</p> Signup and view all the answers

    In what part of the body is the highest number of bacteria found?

    <p>Large intestine</p> Signup and view all the answers

    What is the definition of 'infection'?

    <p>A condition in which pathogenic microbes penetrate host defenses</p> Signup and view all the answers

    Which of the following is NOT a method by which normal microbiota protect the host?

    <p>Exposing tissues to toxins</p> Signup and view all the answers

    Which physiological barrier is primarily involved in recognizing pathogen-associated molecular patterns (PAMPs)?

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

    What does the term 'disease' refer to in a biological context?

    <p>Any deviation from health caused by microbes</p> Signup and view all the answers

    Which of the following statements about transient microbiota is true?

    <p>They can be present for days, weeks, or months.</p> Signup and view all the answers

    What is the primary purpose of the inflammation response?

    <p>To contain damage and restore function</p> Signup and view all the answers

    What defines nonspecific resistance in the immune system?

    <p>General defenses against all pathogens</p> Signup and view all the answers

    Which component enhances the effectiveness of the skin as a barrier?

    <p>Keratin embedded in the outer layers.</p> Signup and view all the answers

    What is a primary factor that influences nonspecific resistance in an individual?

    <p>Dietary habits</p> Signup and view all the answers

    What role do the mucous membranes play in the first line of defense?

    <p>They trap and transport microbes away from sensitive areas.</p> Signup and view all the answers

    Which characteristic best describes adaptive immunity?

    <p>Ability to adapt to new pathogens over time</p> Signup and view all the answers

    Which of the following mechanisms is NOT part of the innate immune system?

    <p>Antibody production by B cells</p> Signup and view all the answers

    What is the primary function of the ciliary escalator in the respiratory tract?

    <p>To trap harmful particles and expel them</p> Signup and view all the answers

    What defines microbial antagonism?

    <p>Healthy microbes competing against harmful microbes</p> Signup and view all the answers

    Which structure of the skin contributes to its protective function?

    <p>Tightly woven fibrous connective tissue</p> Signup and view all the answers

    Which statement best describes the role of barriers in the innate immune system?

    <p>They prevent the entry of pathogens into the host body.</p> Signup and view all the answers

    What does commensalism demonstrate in the relationship between normal microbiota and the host?

    <p>One organism benefits while the other is unaffected</p> Signup and view all the answers

    Which term describes the presence of pathogenic microbes that disrupt host health?

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

    Which of the following describes the role of normal microbiota in the body?

    <p>Occupy niches that pathogens might occupy</p> Signup and view all the answers

    What are opportunistic pathogens?

    <p>Normally non-pathogenic but can cause disease under certain conditions</p> Signup and view all the answers

    What is mutualism in the context of microbiota and the host?

    <p>Both organisms benefit from the interaction</p> Signup and view all the answers

    Where in the human body is the highest concentration of bacteria typically found?

    <p>Large intestine</p> Signup and view all the answers

    What is the main role of inflammation in response to infection?

    <p>Restore function to the affected tissues</p> Signup and view all the answers

    Which of the following statements describes transient microbiota?

    <p>They may be present for a limited time</p> Signup and view all the answers

    Which of the following accurately defines the term disease?

    <p>A disruption of health caused by microbes or their products</p> Signup and view all the answers

    What is the primary purpose of producing bacteriocins by normal microbiota?

    <p>To inhibit the growth of competing bacteria</p> Signup and view all the answers

    Study Notes

    Host Pathogen Interactions - Innate Immune Systems

    • Terminology
      • Susceptibility: Lack of resistance to a disease
      • Resistance: Ability to ward off disease
      • Non-specific resistance: Defenses against any pathogen
      • Specific resistance: Immunity, resistance to a specific pathogen

    Mechanisms of Pathogenicity

    • Pathogenicity is the ability to cause disease
    • Number of invading microbes influences severity
    • Portals of entry: Mucous membranes (respiratory, gastrointestinal, genitourinary tracts, conjunctiva, skin), Parenteral route
    • Penetration or evasion of host defenses: Capsules, cell wall components, enzymes, siderophores, antigenic variation, cytoskeleton
    • Damage to host cells/cytopathic effects: Direct damage, toxins (exotoxins, endotoxins), lysogenic conversion
    • Portals of exit: Generally the same as portals of entry

    Host Defense Mechanisms

    • Defense mechanisms are categorized into innate and adaptive (specific) immunity
    • Non-specific immunity protects against most disease agents, and its function can be influenced by stress, age, and diet
    • Specific immunity protects against a particular pathogen

    Host Defenses

    • Nonspecific Resistance

      • First line of defense: Intact skin, mucous membranes and secretions, normal microbiota
      • Second line of defense: Phagocytic white blood cells, inflammation, fever, antimicrobial substances (complement)

    • Specific Resistance

      • Third line of defense: Specialized lymphocytes (B cells, T cells), antibodies

    • Receptors for Pathogen Recognition

      • Toll-like receptors (TLRs)
      • Complement
      • Pattern recognition

    • Specialized cells

      • Antigen or shape recognition
      • "Learned" or adaptive
      • Intercellular - Humoral
      • Intracellular - Cellular

    Immune System Flow

    • Preformed: Barriers, antimicrobials, microbiota
    • Induced: ... (diagram shows process)

    First Line of Defense

    • Physical barriers: Skin (most visible barrier), mucous membranes (digestive, respiratory, genitourinary tracts)
    • Chemical barriers:
      • Lysozyme in tears and other secretions
      • Acid in stomach (low pH)
      • Antimicrobial factors in saliva (lysozyme, peroxidase, lactoferrin)
      • Skin-physical barrier, fatty acids, sweat, normal flora
      • Rapid pH change from stomach to upper intestine
      • Flushing of the urinary tract
      • Normal flora of the vagina

    Skin

    • Provides the most difficult barrier to penetrate
    • Composed of two main layers: Dermis and epidermis
    • Dermis: Contains tightly woven fibrous connective tissues, making it tough
    • Epidermis: Composed of many layers of epithelial cells, becoming increasingly flat as they reach the surface, outermost sheets embedded with keratin, making it water repellent, outer layers slough off, taking microbes with them.

    Other Factors

    • Mucous membranes and secretions: Ciliary escalator (traps microbes in mucus transported away from the lungs), lacrimal apparatus (washes eye), saliva (washes microbes off), urine (flows out), vaginal secretions (flow out), defecation, vomiting

    Normal Microbiota and the Host

    • Microbial antagonism: Competition between microbes
    • Normal microbiota protect the host by: Occupying niches that pathogens might occupy, producing acids, producing bacteriocins
    • Probiotics: Live microbes applied to or ingested into the body, intended to exert a beneficial effect

    Normal Microbiota and the Host (continued)

    • Transient microbiota: Present for days, weeks, or months
    • Normal microbiota: Permanently colonize the host
    • Symbiosis: Relationship between normal microbiota and the host

    Symbiosis

    • Commensalism: One organism benefits, the other is unaffected
    • Mutualism: Both organisms benefit
    • Parasitism: One organism benefits at the expense of the other
      • Some normal microbiota are opportunistic pathogens

    Infection

    • A condition in which pathogenic microbes penetrate host defenses, enter tissues, and multiply

    Disease

    • Any deviation from health, disruption of a tissue or organ caused by microbes or their products

    Who are these guys? (Pathogens)

    • Includes bacteria, fungi, protozoa, viruses, and arthropods
    • Mostly in contact with the outside environment (large intestine has the highest numbers of bacteria)
    • Internal organs and tissues & fluids are microbe-free
      • Presence of microbes indicates infection

    Physiological Barriers (Second Line Defenses)

    • Blood elements (PAMP recognition)
      • Phagocytes
      • Complement proteins
    • Inflammation response
      • Contain Damage
      • Localize the response
      • Restore function

    How to cells "see" pathogens?

    • Receptors recognize shapes or patterns = PAMPs
      • RNA viruses (TLR3, 7, 8)
      • DNA viruses (TLR9)
      • Gram-positive bacteria (TLR1, 2, 6, LTA-TLR2)
      • Gram-negative bacteria (TLR4, Flagellin-TLR5)
      • Fungi (TLR9)
      • Protists (TLR2, 4)

    Complement Systems

    • Acts in response to stimuli
      • Classical pathway, Lectin pathway, Alternative pathway
    • Activation sets off chain reaction, results in destruction or removal of the invader
    • Effects of complement activation
      • Opsonization (immune adherence)
      • Enhanced phagocytosis
      • Membrane attack complex (Cytolysis)
      • Attract phagocytes

    Next Time

    • Adaptive immune system

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    Innate Immune Systems PDF

    Description

    Test your knowledge on the innate immune systems and the mechanisms of pathogenicity. This quiz covers key terms, host defense mechanisms, and the various ways pathogens interact with the host. Understand concepts such as susceptibility, resistance, and the role of specific and non-specific defenses.

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