There are five organ networks: Metal, Water, Wood, Fire, and Earth. Each is associated with its own meridian and set of functions.
Earth network (土行): the spleen meridian (脾経)
As a minister of agriculture oversees the production and distribution of farm resources, the spleen supplies the nourishment that sustains the organism. The raw material of food and experience is ingested, digested, and assimilated to fuel the life of the body and mind. This fuel, called nutritive essence, is extracted and converted into an abundance of Ki and blood. The earth network gathers and holds together. Like Mother Earth, the spleen is the constant provider, the hearth around which the body gathers to renew itself.