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Lymphatics and Innate Immunity - Anatomy & Physiology

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Terms in this set (21)

  • Primary components of the lymphatic system
    Network of lymphatic vessels, lymph fluid, and lymph nodes that return leaked fluids to blood and cleanse lymph.
  • Functions of lymphatic vessels
    Return interstitial fluid and leaked plasma proteins to blood; lymph flows one-way toward the heart.
  • What are lacteals?
    Specialized lymphatic capillaries in intestinal mucosa that absorb digested fats and deliver fatty lymph (chyle) to the blood.
  • How is lymph transported through lymphatic vessels?
    By skeletal muscle contractions, thoracic pressure changes during breathing, valves preventing backflow, arterial pulsations, and smooth muscle contractions in vessel walls.
  • Main types of lymphocytes and their roles
    T cells moderate immune response and destroy infected cells; B cells produce plasma cells that secrete antibodies.
  • Role of macrophages in lymphatic system
    Phagocytize foreign substances and help activate T cells.
  • Structure of lymph nodes
    Fibrous capsule with trabeculae, cortex with follicles (B cells), deep cortex with T cells, and medullary cords containing B, T, and plasma cells.
  • How does lymph flow through a lymph node?
    Enters via afferent vessels, flows through sinuses to medulla, exits via fewer efferent vessels, allowing immune cells time to act.
  • Functions of the spleen
    Site of lymphocyte proliferation, blood cleansing of aged cells, stores breakdown products of RBCs, platelets, and monocytes.
  • Unique features of the thymus
    Site of T cell maturation, lacks B cells and follicles, most active in childhood, contains thymic corpuscles for regulatory T cell development.
  • What is MALT and its function?
    Mucosa-associated lymphoid tissue protects mucous membranes from pathogens; includes tonsils, Peyer's patches, and appendix.
  • Two lines of innate defense
    1) Surface barriers like skin and mucosae; 2) Internal defenses including phagocytes, natural killer cells, antimicrobial proteins, inflammation, and fever.
  • How do phagocytes destroy pathogens?
    Phagocytes adhere to pathogens, engulf them into phagosomes, fuse with lysosomes to form phagolysosomes, and digest the pathogens.
  • Role of natural killer (NK) cells
    Attack cells lacking 'self' markers, induce apoptosis in cancer and virus-infected cells, and secrete chemicals enhancing inflammation.
  • Cardinal signs of acute inflammation
    Redness, heat, swelling (edema), pain, and impairment of function.
  • Functions of inflammatory mediators
    Dilate arterioles, increase capillary permeability, attract leukocytes, and promote clotting to isolate injured area.
  • Steps of phagocyte mobilization during inflammation
    Leukocytosis, margination, diapedesis, and chemotaxis to the injury site.
  • How do interferons protect against viruses?
    Infected cells secrete interferons that warn neighbors to produce antiviral proteins blocking viral replication and activate NK cells.
  • What is the complement system?
    A group of ~20 blood proteins that enhance inflammation, promote phagocytosis, and cause cell lysis of pathogens.
  • Three pathways of complement activation
    Classical (antibody-mediated), lectin (lectin binding to sugars), and alternative (spontaneous activation).
  • Role of membrane attack complex (MAC)
    Formed by complement proteins inserting into pathogen membranes, creating pores that cause cell lysis.