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Immune System Basics - Anatomy & Physiology

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Terms in this set (26)

  • What is the primary function of the immune system?
    To distinguish 'self' from 'non-self' and protect the body by identifying and eliminating pathogens.
  • What are pathogens?
    Pathogens are disease-causing microorganisms such as viruses, bacteria, parasites, and fungi.
  • What are the two main types of immunity?
    Innate immunity (nonspecific, present at all times) and adaptive immunity (specific, acquired over a lifetime).
  • What are the four main functions of immunity?
    Immunological recognition, immune effector functions, immune suppression, and immunological memory.
  • What are surface barriers in innate immunity?
    Skin and mucous membranes that provide a physical barrier and secrete antimicrobial substances like acid mantle, enzymes, mucin, and defensins.
  • What role do pattern recognition receptors play in innate immunity?
    They recognize common molecular patterns on pathogens, such as Toll-like receptors detecting microbial molecules.
  • How do opsonins assist phagocytosis?
    Opsonins coat pathogens to provide 'handles' that phagocytes can recognize and bind to for easier engulfment.
  • What is the function of natural killer (NK) cells?
    NK cells release perforin to create pores in target cells and granzymes to induce apoptosis, killing infected or abnormal cells.
  • What triggers inflammation in innate immunity?
    Tissue damage and pathogen invasion cause release of inflammatory mediators, leading to vasodilation, increased permeability, and immune cell recruitment.
  • What are interferons and their role?
    Proteins released by virus-infected cells that stimulate nearby cells to block viral replication and activate NK cells and macrophages.
  • What is the complement system?
    A group of proteins that enhance inflammation, opsonize pathogens, and form membrane attack complexes to lyse target cells.
  • How does fever support immune defense?
    Fever raises body temperature setpoint, sequesters iron and zinc to limit bacterial growth, and increases metabolic rate to speed tissue repair.
  • What are the two broad categories of adaptive immunity?
    Humoral immunity (antibody-mediated by B cells) and cellular immunity (T cell-mediated).
  • What is an antigen?
    A substance that can mobilize adaptive immune responses by being recognized by lymphocytes and antibodies.
  • What are antigenic determinants?
    Specific parts of an antigen that antibodies and lymphocytes bind to, also called epitopes.
  • What is the difference between complete antigens and haptens?
    Complete antigens stimulate immune responses alone; haptens are small molecules that become immunogenic only when attached to a carrier protein.
  • How do antigen-presenting cells (APCs) activate T cells?
    APCs engulf antigens and present antigen fragments on MHC proteins to T cells for recognition and activation.
  • What is the difference between MHC class I and class II proteins?
    Class I MHC displays endogenous antigens on all nucleated cells; Class II MHC displays exogenous antigens on APCs.
  • What is the role of helper T (TH) cells?
    TH cells secrete cytokines to activate and enhance other immune cells but do not kill pathogens directly.
  • How do cytotoxic T (TC) cells kill infected cells?
    TC cells release perforin and granzymes to induce apoptosis in infected or abnormal cells.
  • What is the basic structure of an antibody?
    Four polypeptide chains (two heavy, two light) with variable antigen-binding regions and constant regions that determine antibody class.
  • What is immunological memory?
    The adaptive immune system's ability to remember specific pathogens for faster and stronger responses upon re-exposure.
  • What causes immediate hypersensitivity (allergies)?
    Allergens crosslink IgE on mast cells and basophils, triggering histamine release and symptoms like itching, redness, and swelling.
  • What is severe combined immunodeficiency (SCID)?
    A genetic disorder causing deficits in B and/or T cells, leading to severe immune deficiency and vulnerability to infections.
  • How does HIV cause acquired immunodeficiency syndrome (AIDS)?
    HIV infects CD4+ T cells, integrates into their genome, replicates, and destroys these cells, weakening the immune system.
  • What leads to autoimmunity?
    Failure of self-tolerance due to ineffective lymphocyte education, gene mutations, or molecular mimicry causing immune attack on self.