The Lymphatic System

• Functions:

  • Return of tissue fluid to the blood stream.
  • Important part of the body's immune response
• Consists Of:

  • A network of lymph capillaries joined together to larger lymph vessels.
  • Lymph nodes which are located along the length of some lymph vessels.
• Lymph

  • The fluid that is returned to the cardiovascular system by lymphatic vessels
  • Consists of white blood cells, proteins, fats and water.
• Lymph capillaries

  • Begin as blind ended tubes in the spaces between the cells of most tissues.
  • Are usually slightly larger than blood capillaries.
• Lymphatic Vessels

  • Capillaries join to larger vessels
  • Lymph is moved along the vessel by surrounding muscle contractions.
  • Also have valves to prevent backflow.
  • These vessels join up to larger and larger vessels, which eventually link up to lymph ducts that empty lymph into veins.
• Lymph Nodes

  • Located along the lymph vessels
  • Found in clumps in the neck, under the arms and in the groin.
  • Surrounded by a capsule of connective tissue that form a framework extending into the node.
  • Within the framework are masses of lymphoid tissue, containing cells known as lymphocytes, macrophages and plasma cells.
  • Found in:
  • The spleen
  • Thymus gland
  • Tonsils
  • Peyer's patches in the gut
  • Appendix
•  

  Defense

  • Lymph nodes filter lymph
  • Cell debris, foreign particles, micro-organisms and bacteria are destroyed by macrophages (by Phagocytosis)
  • When infections occur, lymph nodes become swollen and sore due to this response.