!Lymphatic System
!!Overview
Lymph is the __interstitial fluid__. It consists of ((Circulatory - Blood|blood plasm)), nutrients and enzymes, as well as particles and cells too large to be transported in the smaller blood vessels. 
The lymphatic system can be broadly divided into the __conducting system__ and the __lymphoid tissue__.
*The conducting system carries the lymph and consists of tubular vessels that include the lymph capillaries, the ((Circulatory - Lymph-Vessels|lymph vessels)), and the right and left thoracic ducts.
*The lymphoid tissue is primarily involved in immune responses and consists of __lymphocytes__ and other white blood cells enmeshed in ((Musculoskeletal - Connective Tissue|connective tissue)) through which the lymph passes. Regions of the lymphoid tissue that are densely packed with lymphocytes are known as ''__lymphoid follicles__''. Lymphoid tissue can either be structurally well organized as ((Circulatory - Lymph-Nodes |lymph nodes)) or may consist of loosely organized lymphoid follicles known as the __mucosa-associated lymphoid tissue__ (((Digestive - Intestinal Lymphatic Tissue|MALT))).
*The central or __primary lymphoid organs generate lymphocytes__ from immature progenitor cells.

The ((Endocrine - Thymus |thymus)) and the ((Musculoskeletal - Bones|bone marrow)) constitute the primary lymphoid tissues involved in the production and early selection of lymphocyte tissues.

Secondary or peripheral lymphoid organs maintain mature naive lymphocytes and initiate an __adaptive immune response__. The peripheral lymphoid organs are the sites of lymphocyte activation by antigen. Activation leads to clonal expansion and affinity maturation. Mature lymphocytes recirculate between the blood and the peripheral lymphoid organs until they encounter their specific antigen.

Secondary lymphoid tissue provides the environment for the foreign or altered native molecules (__antigens) to interact with the lymphocytes__. It is exemplified by the lymph nodes, and the lymphoid follicles in ((Digestive - Tonsils|tonsils)), ((Digestive - Intestinal Lymphatic Tissue|Peyer's patches)), ((Circulatory - Spleen|spleen)), adenoids, skin, etc. that are associated with the mucosa-associated lymphoid tissue (MALT).

The lymphatic system has multiple interrelated functions:
*It is responsible for the __removal of interstitial fluid__ from tissues
*It __absorbs__ and transports fatty acids and fats as chyle from the ((Digestive - System Overview|digestive system))
*It __transports white blood cells__ to and from the lymph nodes into the bones
*The lymph transports antigen-presenting cells (APCs), such as dendritic cells, to the lymph nodes where an __immune response__ is stimulated.

{img fileId="231" thumb="box"} graphic: wikipedia, [https://en.wikiversity.org/wiki/Blausen_gallery_2014|Blausen.staff]

In META-Health, we have a more integrative view of the immune system, as well as of microbes. We perceive the so called immune system as a __powerful and comprehensive intracommunication__ of the organism, initiating and guiding it´s stress and regeneration reactions intelligently and making use of microbial work. To distinguish needed from unwanted substances and information (proteins), and to control the internal processes, we need cell memory and our immune (or perhaps:”__identity integrity guarding__”) system.

!!Brain
{img fileId="202" thumb="box"}

__Cerebral Medulla__ (-/+) for ((Circulatory - Lymph-Vessels|lymph vessels)), ((Circulatory - Lymph-Nodes |lymph nodes)) and ((Circulatory - Spleen|spleen))
{img fileId="175" thumb="box"}

__Midbrain__ (+/0) for ((Organ Walls - Smooth Muscle Layer|smooth muscle layer)) in lymph vessels
compare __Brain Stem__ {img fileId="190" thumb="box"}

For ((Digestive - Tonsils|tonsils)), ((Digestive - Intestinal Lymphatic Tissue|Peyer´s Patches and MALT)), see “((Digestive - System Overview|Digestive System))”
