Objectives 35 and 38: Lymph flow and Lymph and Edema

Well, as you can see from the picture above, from the Anatomy and Physiology Laboratory Manual**, I took alot of notes in lab that day!  Understanding lymph flow goes back to the process of diffusion for me.  The understanding that fluids (especially one that is primarily water) will follow salt (or solutes) and that molecules will move from an area of higher concentration to lower concentration.  The operation of moving lymph from the interstitial fluid into the lymphatic capillaries works on this same principal, the lymph essentially moves because of a pressure gradient. When the fluid pressure outside of the lymphatic capillaries is higher on the outside, lymph flows in. How does it move through the body?  Because there is no pump for the lymph fluid, it moves through the body very much the same way that blood returns from the distal limbs to the heart; through skeletal muscle contraction and change in pressure due to respiration. Understanding that the lymph node pictured above is essentially a large filter for all of the junk (no, thats not the technical term) that your body has to process; its easy to understand that the nodes can sometimes become "backed up".  This backing up of the lymph fluid can cause localized edema.

Nurses Note: Metastasizing cancers can get trapped in the lymph nodes and cause the nodes to become a secondary cancer site.  The surrounding lymph nodes are often removed in many cancer treatments.