1540s, belonging to an ecclesiastical metropolis, from Late Latin metropolitanus, from Greek metropolites resident of a city, from metropolis (see metropolitan (n.)). Meaning belonging to a chief or capital city is from 1550s. In reference to underground city railways, it is attested from 1867.
The solution that runs through these vessels, called lymph, begins in the circulatory system as blood plasma and then is converted to a fluid known as an interstitial or intercellular fluid. This fluid is responsible for delivering hormones, oxygen, and various nutrients to cells throughout the body.fferent vessels transport fluid into the lymph nodes, while efferent vessels carry filtered lymph away from the lymph nodes. White blood cells called lymphocytes are a major part of the lymphatic system. Lymph nodes may become swollen when a person gets sick.
Lymph nodes serve two major functions in the body. They filter lymph and assist the immune system in building an immune response. Lymph is a clear fluid that comes from blood plasma that exits blood vessels at capillary beds.This fluid becomes the interstitial fluid that surrounds cells.ymphoma is the term used for cancer that begins in the lymphatic system. This type of cancer originates in the lymphocytes that inhabit lymph nodes and lymph tissues. Lymphomas are grouped into two main types: Hodgkin's lymphoma and Non-Hodgkin lymphoma (NHL) .