There are five organ networks: Metal, Water, Wood, Fire, and Earth. Each is associated with its own meridian and set of functions.
Metal network (金行): the lung meridian (肺経)
In the lung, the Ki of heaven joins with the Ki of earth forming the Ki that vitalizes human life. Like a minister who conducts affairs of state and determines territorial borders, the lung governs the relationship between the inside and the outside, setting limits and protecting boundaries. With restraint and delicacy, expanding and contracting, the lung collects, mixes, and scatters the Ki, instilling rhythm and order.