Lymphatic System

So last time we talked about how the body is able to fight off different bacteria and viruses.  This is all part of an immune defense that our body has called the lymphatic system.  The lymphatic system itself is made up of a fluid called lymph.  The lymphatic system is made up of many lymphatic vessels that transport this lymph, a number of organs and structures containing lymphatic tissue, and red bone marrow.  The red bone marrow is where the stem cells develop into the various types of blood cells, including the lymphocytes.  It is the lymphatic systems job to assist in circulating body fluids that helps to defend the body against many disease causing agents.  The majority of the blood plasma filters out of blood capillary walls to form interstitial fluid, and this is the fluid that surrounds the cells of body tissues.  After this fluid passes into the lymphatic tissues, however, it is then called lymph and is a clear fluid.  The only major difference between the interstitial fluid and lymph is its location.  Interstitial fluid is found between the cells, and lymph is found within lymphatic vessels and lymphatic tissue.  

We learned that lymphatic tissue is a specialized form of reticular connective tissue that contains large numbers of lymphocytes.  We also learned previously that lymphocytes are agranular white blood cells.  The two types of lymphocytes that participate in the immune system are the B cells and the T cells. 

 There are three main functions that the lymphatic system plays in the body.  The first function is that it drains excess interstitial fluid.  The lymphatic vessels drain the excess fluid from the tissue spaces and return it to the blood.  The second main function of the lymphatic system is that it transports dietary lipids.  Lymphatic vessels transport lipids and lipid-soluble vitamins that are absorbed by the GI tract back to the blood.  These vitamins would include A, D, E, and K.  The third primary function of the lymphatic system is that it carries out our immune responses.  Lymphatic tissue initiates highly specific responses directed against particular microbes or abnormal cells.