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Immune System: Innate and Adaptive Defenses - Anatomy & Physiology

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Termini in questo insieme (20)

  • What are the two main types of immune defenses?
    The immune system has innate (nonspecific) defenses and adaptive (specific) defenses that work together to protect the body.
  • What constitutes the first line of defense in innate immunity?
    Physical and chemical barriers such as skin, sebum, stomach acid, mucus in respiratory tract, and acidic urine prevent pathogen entry.
  • What role do phagocytic cells play in innate immunity?
    Phagocytic cells like neutrophils and macrophages ingest and destroy pathogens in tissues and blood.
  • What is the function of endogenous pyrogens?
    Endogenous pyrogens induce fever, which slows bacterial growth and enhances immune responses.
  • Name key internal defenses of innate immunity.
    Phagocytosis, natural killer (NK) cells, inflammatory response, and antimicrobial proteins like complement and interferons.
  • What is the complement system?
    A group of proteins that enhance inflammation, opsonize pathogens, and form the Membrane Attack Complex (MAC) to lyse bacteria.
  • What are antigens?
    Large, complex proteins that trigger antibody production or specific immune responses; can be foreign or self-antigens like MHC proteins.
  • What is the difference between Class I and Class II MHC molecules?
    Class I MHC is on all nucleated cells and presents endogenous antigens to cytotoxic T cells. Class II MHC is on antigen-presenting cells and presents exogenous antigens to helper T cells.
  • Describe the structure of an antibody.
    Y-shaped protein with two heavy chains and two light chains, each antibody has two antigen-binding sites.
  • What cells produce antibodies?
    B lymphocytes (B cells) produce antibodies as part of the humoral immune response.
  • What is the primary immune response?
    The initial production of antibodies by B cells upon first exposure to an antigen; slower and less intense.
  • What is the secondary immune response?
    A faster and stronger antibody response upon subsequent exposure to the same antigen due to memory B cells.
  • Differentiate active and passive immunity.
    Active immunity involves the body producing its own antibodies; passive immunity involves receiving antibodies from another source.
  • List functions of antibodies.
    Antibodies fix complement, neutralize pathogens, and cause agglutination to enhance pathogen removal.
  • Name the five main classes of immunoglobulins.
    IgA, IgD, IgE, IgG, and IgM, each with distinct functions and body locations.
  • What is the role of cytotoxic T cells (CD8+)?
    They recognize antigens on Class I MHC and destroy infected or abnormal cells by releasing perforin and cytotoxins.
  • What is the role of helper T cells (CD4+)?
    Helper T cells activate B cells and cytotoxic T cells by releasing cytokines like interleukin-2 (IL-2) and recognize antigens on Class II MHC.
  • How do helper T cells coordinate the immune response?
    They provide costimulatory signals necessary for activation and proliferation of B cells and cytotoxic T cells.
  • What causes immunodeficiencies?
    Primary immunodeficiencies are genetic (e.g., SCID), while acquired immunodeficiencies like AIDS result from infections that destroy immune cells.
  • What are Type I and Type IV hypersensitivities?
    Type I is an immediate IgE-mediated allergic reaction; Type IV is a delayed reaction mediated by cytotoxic T cells.