The Lymphatic System

• What is the function of the Lymphatic System?

  Drains excess fluids and proteins from tissues back to blood stream which prevents tissue swelling

  Part of the immune system

  Lymph nodes act as filter trapping foreign particles​

  macrophages destroy particles such as bacteria​

  Lymphocytes are responsible for the production of antibodies
• What is the lymphatic system made of?

  A network of lymph capillaries and vessels

  Lymph nodes located along the lymph vessels

  But no pump
• Lymph Capillaries

  Structure- blinds ends (no definite end to capillary)

  Larger and more permeable than blood capillaries which allows for proteins and disease causing organisms in the extracellular fluid to easily pass through the walls of the lymph capillaries into the lymph.
• Lymph vessels

  Join to form two main ducts which return the lymph to the circulatory system via subclavian veins which then form the superior vena cava.

  Lymph moves along the vessels. The smooth muscle layer of the vessels contract to push the lymph along. Lymph moves due to muscle contractions.

  Have no valves to prevent backflow of lymph.
• Lymph Nodes

  Lymph glands are found at intervals along the lymph vessels.

  Bean-shaped

  structures

  Contains lymphoid tissue

  Spaces between cells of lymphoid tissue are criss-crossed by a network of fibres
• Tissue Fluid

  Origin:​

  Tissue fluid comes from substances that leak out of capillaries due to the high pressure in these vessels​

  Destination​:

  Lymph does not circulate​

  The lymphatic system is a one way system that empties into the large veins of the upper chest.
• Lymph Capillaries

  Drainage from the tissue fluid begins at lymph capillaries​

  -a fine mesh of small thin-walled lymph capillaries​

  Tissue fluid diffuses into these capillaries and becomes lymph​

  Lymph is a clear yellow liquid