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Immune System: Innate and Adaptive Immunity

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Terms in this set (20)

  • What are the main steps of phagocytosis?
    1. Phagocyte adheres to pathogen or debris.
    2. Phagocyte engulfs particles forming a phagosome.
    3. Phagosome fuses with lysosome forming a phagolysosome.
    4. Lysosomal enzymes digest particles.
    5. Exocytosis removes indigestible residue.
  • What are the four cardinal signs of inflammation?
    • Redness
    • Heat
    • Swelling
    • Pain
  • Describe the steps of neutrophil mobilization during inflammation.
    1. Leukocytosis: neutrophils enter bloodstream.
    2. Margination: neutrophils cling to capillary walls.
    3. Diapedesis: neutrophils flatten and squeeze out of capillaries.
    4. Chemotaxis: neutrophils follow chemical trail to damage site.
  • What is an antigen and what are antigenic determinants?

    An antigen is a substance that provokes an adaptive immune response. Antigenic determinants are specific parts of the antigen where antibodies or lymphocytes bind.

  • What is the difference between humoral and cell-mediated immunity?

    Humoral immunity involves antibodies produced by B cells. Cell-mediated immunity involves T cells directly killing infected cells or producing chemicals to damage cells.

  • What are the two main types of active humoral immunity?
    • Naturally acquired: response to infection.
    • Artificially acquired: response to vaccine with dead or attenuated pathogens.
  • What is passive humoral immunity and its two types?
    • Naturally acquired: antibodies passed from mother to fetus or infant.
    • Artificially acquired: injection of antibodies like gamma globulin.
  • Describe the basic structure of an antibody.

    Antibodies have 2 heavy chains and 2 light chains connected by disulfide bonds. The variable region forms the antigen-binding site, and the constant region is the same for each antibody.

  • List the four main actions of antibodies.
    • Neutralization: block dangerous parts of pathogens.
    • Agglutination: bind multiple antigens.
    • Precipitation: clump soluble antigens.
    • Complement activation: triggers inflammation and cell lysis.
  • What is the role of helper T cells in immunity?

    Helper T cells mobilize both humoral and cellular immunity by signaling B cells to produce antibodies and CD8 cells to become cytotoxic T cells.

  • What is the difference between MHC class I and class II proteins?
    • Class I MHC: displayed by all cells except RBCs, present endogenous antigens to CD8 cytotoxic T cells.
    • Class II MHC: displayed by antigen-presenting cells, present exogenous antigens to CD4 helper T cells.
  • Explain MHC restriction in T cell activation.

    CD4 T cells bind only to class II MHC proteins on APCs, while CD8 T cells bind only to class I MHC proteins. Cytotoxic T cells then seek the same antigen on any cell with class I MHC.

  • How do cytotoxic T cells kill target cells?
    1. Bind antigen on MHC I proteins.
    2. Release perforin to form pores in target membrane.
    3. Release granzymes that enter pores and trigger apoptosis.
    4. Detach and seek new targets.
  • What is the function of regulatory T cells?

    Regulatory T cells suppress the immune response and help prevent autoimmune diseases.

  • What causes Severe Combined Immunodeficiency (SCID)?

    SCID is a genetic defect causing a marked deficit in B and T cells due to defective adenosine deaminase enzyme, leading to toxic metabolite accumulation that kills T cells.

  • How does HIV cause Acquired Immune Deficiency Syndrome (AIDS)?

    HIV infects and destroys helper T cells, crippling cellular immunity. It uses reverse transcriptase to integrate viral DNA into host cells, leading to immune collapse and opportunistic infections.

  • What are common treatments for HIV/AIDS?
    • Fusion inhibitors block viral entry.
    • Integrase inhibitors block viral DNA integration.
    • Reverse transcriptase and protease inhibitors block viral replication enzymes.
  • What causes autoimmune diseases?

    Autoimmune diseases occur when the immune system loses self-tolerance, producing autoantibodies and sensitized T cells that attack body tissues.

  • What are some treatments for autoimmune diseases?
    • Immune suppression with anti-inflammatory drugs.
    • Blocking cytokine action or co-stimulatory molecules.
    • Research into activating regulatory T cells and inducing self-tolerance.
  • How can foreign antigens trigger autoimmune diseases?

    Foreign antigens may resemble self-antigens, causing cross-reactive antibodies, or new self-antigens may appear due to mutations, hapten attachment, or tissue damage.