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Immune System: Innate and Adaptive Defenses - Anatomy & Physiology

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  • What are the two intrinsic systems of the immune system?
    The immune system consists of the innate (nonspecific) defense system and the adaptive (specific) defense system.
  • What constitutes the first line of defense in innate immunity?
    The first line of defense includes external body membranes such as the skin and mucous membranes.
  • What are the main components of the second line of defense in innate immunity?
    The second line of defense includes phagocytes, natural killer cells, inflammation, antimicrobial proteins, and fever.
  • How do surface membranes provide protection in the first line of defense?
    Surface membranes act as mechanical barriers and produce secretions like acidity, lysozyme, mucus, and defensins that inhibit microbial growth.
  • What is the role of keratin in the skin's defense?
    Keratin provides resistance against weak acids, bases, bacterial enzymes, and toxins.
  • Describe the process of phagocytosis.
    Phagocytosis involves recognition, adherence, engulfment, digestion of pathogens, and exocytosis of indigestible material.
  • What is opsonization in phagocytosis?
    Opsonization is when antibodies or complement proteins coat pathogens, enhancing phagocyte binding and engulfment.
  • What are natural killer (NK) cells and their function?
    NK cells are large granular lymphocytes that kill virus-infected and cancerous cells by inducing apoptosis.
  • What are the four cardinal signs of acute inflammation?
    The four cardinal signs are redness, heat, swelling, and pain. Impaired function may be a fifth sign.
  • What triggers the inflammatory response?
    Inflammation is triggered by tissue injury caused by trauma, heat, chemicals, or infections.
  • What are the three stages of inflammation?
    The stages are inflammatory chemical release, vasodilation and increased vascular permeability, and phagocyte mobilization.
  • Name key inflammatory chemicals released during inflammation.
    Key chemicals include histamine, kinins, prostaglandins, complement, and cytokines.
  • How does fever enhance the immune response?
    Fever inhibits pathogen reproduction, increases metabolic rate, enhances phagocyte activity, and promotes sequestration of iron and zinc.
  • What are interferons and their role?
    Interferons are proteins secreted by virus-infected cells that warn neighboring cells to produce antiviral proteins.
  • What is the complement system and its functions?
    The complement system is a group of plasma proteins that enhance phagocytosis, promote inflammation, and cause cell lysis.
  • Describe the membrane attack complex (MAC).
    MAC is formed by complement proteins that create pores in microbial membranes, causing cell lysis.
  • What are antigens?
    Antigens are substances that mobilize adaptive defenses and provoke an immune response.
  • What are antigenic determinants?
    Antigenic determinants are specific parts of an antigen that antibodies or lymphocyte receptors bind to.
  • What are MHC proteins and their role?
    MHC proteins are glycoproteins on cell surfaces that present antigen fragments to T cells and mark cells as self.
  • What are the main types of lymphocytes in adaptive immunity?
    The main lymphocytes are B cells (humoral immunity) and T cells (cellular immunity).
  • Outline the five general steps of lymphocyte development and activation.
    Steps: origin, maturation and education, seeding, activation, and proliferation.
  • What is clonal selection in lymphocytes?
    Clonal selection is when a lymphocyte binds its specific antigen, triggering proliferation and differentiation into effector and memory cells.
  • What is the difference between active and passive humoral immunity?
    Active immunity involves B cells producing antibodies after antigen exposure; passive immunity involves receiving antibodies from another source.
  • Describe the basic structure of an antibody.
    An antibody is a Y-shaped protein with two heavy and two light chains, containing variable and constant regions.
  • Name the five major classes of antibodies.
    The classes are IgM, IgA, IgD, IgG, and IgE.
  • What are the main functions of antibodies?
    Antibodies neutralize antigens, agglutinate, precipitate, activate complement, and tag antigens for destruction.
  • What are the roles of helper T cells?
    Helper T cells activate B cells, other T cells, macrophages, and release cytokines to coordinate immune responses.
  • What is the function of cytotoxic T cells?
    Cytotoxic T cells directly kill infected, cancerous, or foreign cells by inducing apoptosis.
  • What role do regulatory T cells play?
    Regulatory T cells maintain immune tolerance and suppress excessive immune responses.