Chapter 20: Lymphatic system

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Chapter 20: Lymphatic system
2014-04-23 18:29:41
lymphatic system
Anatomy and Physiology
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  1. Lymphatic System
    • Returns fluids that leaked from blood vessels back to blood
    • 3 Parts - lymphatic vessels, lymph, lymph nodes
  2. Lymphoid Organs and Tissues
    • Structural basis of immune system
    • House phagocytic cells and lymphocytes
    • Structures - spleen, thymus, tonsils, other lymphoid tissues
  3. Lymphatic Vessels
    • Return interstitial fluid and leaked plasma proteins back to blood
    • One way-system; lymph flows toward heart
    • ~ 3L / day
    • Lymphatics include - lymphatic capillaries, collecting lymphatic vessels, lymphatic trunks and ducts
  4. Lymph
    • Fluid in the lymphatics
    • [leaks out of capillaries]
  5. Lymphatic Capillaries
    Very permeable (taking up proteins, cell debris, pathogens, and cancer cells)
  6. Lacteals
    • specialized lymph capillaries present in intestinal mucosa
    • Absorb digested fat and deliver fatty lymph to the blood
  7. Lymphatic Collecting Vessels
    • Similar to veins, except - they have thinner walls with more internal valves, anastomose more frequently
    • Collecting vessels in skin travel with superficial veins
    • Deep vessels travel with arteries
    • Lymphatic vessels drain into lymphatic trunks
  8. Lymphatic Ducts
    • Lymphatic delivered into one of two large ducts (right lymphatic duct, thoracic duct)
    • Each empties lymph into venous circulation at junction of internal jugular and subclavian veins on its own side of body
  9. Right Lymphatic Duct
    Thoracic duct
    • Drains right upper arm and right side of head and thorax
    • Drains rest of body
  10. Lymph Transport - lymph propelled by
    • Milking action of skeletal muscle
    • Pressure changes in thorax during breathing
    • Valves prevent backflow
    • Pulsations of nearby arteries
    • Contractions of smooth muscle in walls of lymphatics
  11. Lymphoid Cells
    Lymphocytes - main warriors of immune system - mature into one of two main varieties (B cells - humoral immunity, T cells - cell-mediated immunity)
  12. Lymphocytes - T Cells
    • Manage immune response
    • Attack and destroy infected cells
    • [attack cells]
  13. Lymphocytes - B cells
    • Product plasma cells, which secrete antibodies
    • [defense cells]
  14. Antibodies
    mark antigens for destruction
  15. Macrophages
    • Phagocytize foreign substances
    • Help activate T cells
    • [antigen-preventing cells]
  16. Dendritic Cells
    capture antigens and deliver them to lymph nodes
  17. Lymph Node - Functions
    • 1. Filter lymph
    • 2. Immune system activation - lymphocyte activated and mount attack against antigen
  18. Lymph Node - Structure
    • Medullary cords extend inward from  cortex and contain B cells, T cells, and plasma cells
    • Nodes are embedded in the connective tissue!
  19. Lymph sinuses
    contain macrophages
  20. Spleen Functions - Largest lymphoid organ
    • Site of lymphocyte proliferation and immune surveillance and response
    • Cleanses blood of aged cells and platelets, macrophages remove debris
    • Stores products of RBC destruction for reuse
    • Stores platelets and monocytes until needed
    • [storage unit]
  21. Thymus
    • Important functions early in life
    • Increases in size and most active during childhood
  22. Mucosa-associated Lymphoid  Tissue (MALT)
    • Lymphoid tissues in mucous membranes hroughout body
    • Protects from pathogens trying to enter body
    • Largest collections of MALT in tonsils, Peyer's patches, appendix
    • Also in mucosa of respiratory and genitourinary organs; rest of digestive tracts
  23. Tonsils - simplest lymphoid organs
    • Gather and remove pathogens from food and air
    • Form ring of lymphatic tissue around pharynx
    • Palatine tonsils - at posterior end of oral cavity
    • Lingual tonsil - grouped at base of tongue
    • Pharyngeal tonsil - in posterior wall of nasopharynx (adenoids)
    • Tubal tonsils - surrounding openings of auditory tubes into pharynx
  24. Peyer's Patches
    • Clusters of lymphoid follicles
    • In wall of distal portion of small intestine
    • Similar structures are also found in the appendix
  25. Peyer's patches and appendix
    • Destroy bacteria, preventing them from breaching intestinal wall
    • Generate "Memory lymphocytes"