Some science behind the scenes

Lymph system

lymph system
Lymph system
Source: Wikipedia commons

The lymph system is an extensive network of vessels that resemble veins, but which are not either  arteries or veins. 

The system contains a colourless or pale yellow liquid that is called lymph (from Latin lympha "water goddess") which has a composition similar to tissue fluid [the fluid found in and bathing cells] but it contains more fatty substances, protein and white blood cells.

Around the body are a number of organs which connect up the system, the largest of which is the spleen.  Other organs include the adenoids, tonsils, appendix and vessels within the bone marrow.

Along with these larger organs are numerous little sacs called lymph nodes .  This network of conduits called lymphatic vessels that carry the lymph uni-directionally towards the heart.

Functionally it plays a key part in our defences against disease.  The lymph nodes help to protect us against disease in a number of ways.

  • They produce and store white blood cells called lymphocytes.  When foreign bodies invade the body, these white blood cells multiply rapidly and become very active engulfing bacteria and secreting antibodies to kill them [the accumulation of white blood cells and dead bacteria can cause the lymph nodes to become swollen and tender but all this shows is that we have been under sever attack]
  • The lymph nodes also filter out foreign particles, bacteria and dead tissue before these  enter the blood stream

Like the blood circulatory system, the lymphatic system is a closed system.  Fluid enters through the walls of lymphatic vessels which can stretch to hold more fluid as necessary.  The lymphatic system has no heart to pump lymph around the body.  Lymphatic vessels can contract, but the circulation of lymph depends mainly on external pressures, lymph is squeezed along vessels by the pressure of body movement  - breathing, intestinal movement, skeletal muscle movement.  So exercise and breathing helps the lymph system!


For iPad/iPhone users: tap letter twice to get list of items.