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Lymphatic and Immune System - Anatomy & Physiology

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  • What are the three main parts of the lymphatic system?
    A network of lymphatic vessels, lymph, and lymph nodes.
  • What is lymph?
    Interstitial fluid that has entered lymphatic vessels.
  • What is the function of the lymphatic system?
    Returns interstitial fluid and leaked plasma proteins back to the blood and provides the structural basis of the immune system.
  • How do lymphatic vessels differ from blood vessels?
    Lymphatic vessels form a one-way system that flows toward the heart and have thinner walls with more valves.
  • What are lymphatic capillaries and their special features?
    Blind-ended tubes with overlapping endothelial cells forming one-way minivalves; very permeable to cell debris, pathogens, and cancer cells.
  • Where are lymphatic capillaries absent?
    Bones, teeth, bone marrow, and the central nervous system.
  • What are lacteals?
    Specialized lymphatic capillaries in the intestinal mucosa that absorb digested fats and deliver fatty lymph (chyle) to the blood.
  • What are the two main lymphatic ducts and their drainage areas?
    Right lymphatic duct drains the right upper arm and right side of the head and thorax; thoracic duct drains the rest of the body.
  • How is lymph transported through lymphatic vessels?
    By skeletal muscle milking, thoracic pressure changes during breathing, valves preventing backflow, arterial pulsations, and smooth muscle contractions.
  • What are the main lymphoid cells involved in immunity?
    T lymphocytes (T cells) and B lymphocytes (B cells).
  • What are the functions of T cells and B cells?
    T cells manage immune response and destroy foreign cells; B cells produce plasma cells that secrete antibodies.
  • What is the role of macrophages and dendritic cells in lymphoid tissue?
    Macrophages phagocytize foreign substances and help activate T cells; dendritic cells capture antigens and deliver them to lymph nodes.
  • What are the two main functions of lymph nodes?
    Filter lymph by destroying microorganisms and debris; activate lymphocytes to mount an immune response.
  • What are the primary functions of the spleen?
    Lymphocyte proliferation, immune surveillance, blood cleansing of aged cells and debris, and blood platelet storage.
  • How does the thymus differ from other lymphoid organs?
    It functions strictly in T lymphocyte maturation and does not directly fight antigens.
  • What are the four types of tonsils and their function?
    Palatine, lingual, pharyngeal, and tubal tonsils; they form a ring around the pharynx to gather and remove pathogens entering via food or air.
  • What are Peyer's patches and their role?
    Clusters of lymphoid follicles in the small intestine wall that destroy bacteria and generate memory lymphocytes.
  • What are the two intrinsic defense systems of immunity?
    Innate (nonspecific) defense system and adaptive (specific) defense system.
  • What are the components of innate surface barriers?
    Skin and mucous membranes with protective chemicals like skin acidity, dermcidin in sweat, HCl in the stomach, lysozyme in saliva, and mucus.
  • What are the main internal innate defenses?
    Phagocytes, natural killer cells, inflammation, antimicrobial proteins, and fever.
  • What is opsonization in phagocytosis?
    Coating of pathogens by complement proteins or antibodies to facilitate phagocyte adherence.
  • What are the cardinal signs of acute inflammation?
    Redness, heat, swelling, pain, and sometimes impairment of function.
  • What are the steps of phagocyte mobilization during inflammation?
    Leukocytosis, margination, diapedesis, and chemotaxis.
  • How do interferons protect against viral infections?
    They are secreted by infected cells and induce neighboring cells to produce antiviral proteins that block viral reproduction.
  • What are the benefits of a moderate fever?
    Causes liver and spleen to sequester iron and zinc, and increases metabolic rate to speed up repair.
  • What are the two arms of adaptive immunity?
    Humoral (antibody-mediated) immunity by B cells and cellular (cell-mediated) immunity by T cells.
  • What are antigens?
    Substances that mobilize adaptive defenses and provoke an immune response.
  • What is the difference between active and passive humoral immunity?
    Active immunity involves B cells producing antibodies after antigen exposure; passive immunity involves receiving antibodies without antigen challenge.
  • What is the structure of an antibody?
    A T- or Y-shaped monomer with two identical heavy chains and two identical light chains, with variable regions forming antigen-binding sites.
  • What are the main functions of antibodies?
    Neutralization, agglutination, precipitation, and complement fixation to inactivate and tag antigens.
  • What are the major types of T cells and their roles?
    Helper T cells activate immune responses; cytotoxic T cells kill infected or abnormal cells; regulatory T cells suppress immune responses; memory T cells provide long-term immunity.