ch5.4 lymphatic system

• lymphatic system = a system of vessels that drain excess fluid from the tissues; an important part of body's internal defence against disease-causing organisms
• consists of:

  • lymph capillaries joined to larger lymph vessels
  • lymph nodes
• lymph vessels return excess tissue fluid to the blood
• lymph is the clearish fluid transported through lymph vessels
• lymph vessels are blind ended tubes meaning lymph does not circulate
• lymph vessels join to form 2 lymph ducts that empty lymph into large vein
• lymph is moved by smooth and skeletal muscle + valves
• lymph nodes occur at intervals along lymphatic vessels and are surrounded by connective tissue forming a framework of:

  • lymphoid tissue
  • lymphocytes
  • macrophages
  • plasma cells
• lymph can contain cell debris, foreign particles + mircoorganisms

  • larger particles are trapped in network fibres and destroyed by phagocytic cells called macrophages
  • when infections occur lymph nodes swell up due to increase in production of lymphocytes