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Anatomy & Physiology: Lymphatic and Immune Systems

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Terms in this set (21)

  • What are the main components of the lymphatic system?
    Lymph (fluid), lymphatic vessels (transport lymph), lymphatic tissue (lymphocytes in connective tissue), and lymphatic organs (organized masses of lymphatic tissue).
  • What are the three primary functions of the lymphatic system?
    Fluid recovery, immunity, and lipid absorption.
  • How much fluid do blood capillaries reabsorb and how much is absorbed by the lymphatic system?
    Blood capillaries reabsorb about 85% of fluid; the remaining 15% is absorbed by the lymphatic system.
  • What role does the lymphatic system play in immunity?
    It checks recovered fluid for pathogens, guards openings to the environment, and mobilizes immune cells to fight detected pathogens.
  • What are lacteals and their function?
    Lacteals are special lymph vessels in the small intestine that absorb dietary lipids and drain them into the bloodstream.
  • Describe the structure of lymphatic capillaries.
    Closed at one end, with loosely connected overlapping cells forming valves and large gaps to allow passage of proteins, bacteria, and white blood cells.
  • What are the two main collecting ducts of the lymphatic system?
    The right lymphatic duct and the thoracic duct.
  • How is lymph moved through lymphatic vessels without a pump?
    By rhythmic contraction of vessel walls, skeletal muscle contractions, thoracic pressure changes during breathing, and blood flow at drainage points.
  • What is MALT in the lymphatic system?
    Mucosa-associated lymphatic tissue, aggregates of lymphocytes in mucous membranes of respiratory, digestive, urinary, and reproductive tracts.
  • What is the function of the thymus?
    Located above the heart, it contains T cells and secretes hormones that promote their development and activity.
  • What is the primary function of the spleen?
    To filter blood, cleanse it of bacteria and foreign matter, and house monocytes; also known as the RBC graveyard.
  • How do lymph nodes function in immunity?
    They filter and cleanse lymph, activate immune responses, and slow lymph flow to allow time for cleansing.
  • What are the three lines of defense in the immune system?
    Surface barriers, innate internal defenses, and adaptive defense system.
  • What constitutes the first line of defense in immunity?
    The intact skin and mucous membranes acting as physical barriers to keep invaders out.
  • What cells are involved in the innate internal defenses?
    Five leukocytes: neutrophils, eosinophils, basophils, monocytes/macrophages, and natural killer cells.
  • What are interferons and their role?
    Proteins secreted by infected cells that signal nearby cells to inhibit viral replication and activate natural killer cells.
  • What is the complement system?
    A group of liver-made proteins in blood that activate a cascade leading to destruction of invading microbes and complement antibodies.
  • What are the four cardinal signs of acute inflammation?
    Redness, heat, swelling, and pain.
  • What causes vasodilation and increased vascular permeability during inflammation?
    Inflammatory chemicals released by injured tissue and immune cells dilate arterioles and make capillaries leakier.
  • Describe the four steps of phagocyte mobilization during inflammation.
    1. Leukocytosis: WBC increase; 2. Margination: phagocytes cling to vessel walls; 3. Diapedesis: WBCs squeeze through endothelium; 4. Chemotaxis: WBCs move toward injury.
  • How does fever support innate immunity?
    Fever inhibits bacterial and viral reproduction, promotes interferon activity, speeds tissue repair, and is triggered by pyrogens from leukocytes.