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Anatomy & Physiology: The Lymphatic System and Body Defenses

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Terms in this set (26)

  • Primary components of the lymphatic system
    The lymphatic system consists of lymphatic vessels, lymph nodes, and certain other lymphoid organs such as the thymus, spleen, tonsils, and Peyer’s patches.
  • Source and formation of lymph
    Lymph is formed from excess interstitial fluid picked up by extremely porous lymph capillaries and transported through lymphatic vessels back to the bloodstream.
  • Function of lymph nodes
    Lymph nodes filter lymph, serve as multiplication sites for lymphocytes, and contain phagocytic cells that remove bacteria, viruses, and debris before lymph returns to the blood.
  • Role of the thymus in immunity
    The thymus programs T lymphocytes to become immunocompetent and self-tolerant, overseeing cell-mediated immunity.
  • Innate (nonspecific) body defenses
    Includes physical barriers like skin and mucous membranes, chemical secretions, natural killer cells, phagocytes, complement proteins, interferons, inflammation, and fever.
  • Function of natural killer (NK) cells
    NK cells nonspecifically lyse virus-infected, malignant, or abnormal cells without prior sensitization.
  • Inflammatory response purpose
    Prevents spread of harmful agents, disposes of pathogens and dead cells, and promotes tissue healing.
  • Phagocytes and their role
    Phagocytes like macrophages and neutrophils engulf and destroy pathogens, enhanced by antibodies and complement attachment.
  • Complement system functions
    Complement proteins fix on foreign cell membranes causing lysis, enhance phagocytosis, and amplify inflammatory and immune responses.
  • How fever protects the body
    Fever increases metabolism to speed repair and causes liver and spleen to store iron and zinc, limiting bacterial growth.
  • Definition of antigen and hapten
    An antigen is a large molecule recognized as foreign; a hapten is a small molecule that triggers an immune response only when attached to a body protein.
  • Two arms of adaptive immunity and their lymphocytes
    Humoral immunity is mediated by B cells producing antibodies; cellular immunity is mediated by T cells targeting infected cells.
  • Development sites of B and T cells
    B cells develop immunocompetence in the bone marrow; T cells develop in the thymus.
  • Role of antigen-presenting cells (APCs)
    APCs like macrophages and dendritic cells phagocytize pathogens and present antigen fragments to T cells to initiate adaptive immunity.
  • Primary humoral immune response
    Clonal selection of B cells produces plasma cells that secrete antibodies and memory cells for future rapid responses.
  • Difference between active and passive immunity
    Active immunity is produced by the body with memory; passive immunity is from antibodies received externally without memory.
  • Structure of an antibody monomer
    An antibody has four polypeptide chains (two heavy, two light) forming a Y-shaped molecule with variable antigen-binding sites and constant regions.
  • Five classes of antibodies
    IgM, IgA, IgD, IgG, and IgE differ in structure and function in immune responses.
  • Functions of antibodies
    Antibodies cause agglutination, complement fixation, neutralization, opsonization, and precipitation of antigens.
  • Roles of helper, regulatory, and cytotoxic T cells
    Helper T cells activate B and T cells; regulatory T cells suppress immune responses; cytotoxic T cells kill infected or foreign cells.
  • Types of organ grafts
    Autograft: from self; isograft: from identical twin; allograft: from another person; xenograft: from different species.
  • Causes of autoimmune diseases
    Autoimmune diseases occur when self-tolerance breaks down and immune cells attack the body's own tissues.
  • Examples of autoimmune diseases
    Rheumatoid arthritis, multiple sclerosis, Graves’ disease, type 1 diabetes, systemic lupus erythematosus, and myasthenia gravis.
  • Most serious immunodeficiencies
    Severe combined immunodeficiency disease (SCID) and acquired immune deficiency syndrome (AIDS), caused by HIV infecting helper T cells.
  • Origin of lymphatic vessels
    Lymphatic vessels form by budding off veins during embryonic development.
  • Effect of aging on immunity
    Immune efficiency declines with age, increasing susceptibility to infections, cancer, immunodeficiencies, and autoimmune diseases.