Chapter 8 of the Suwen: The Bladder

膀 胱 者 ， 州 都 之 官 ， 津 液 藏 焉 ， 氣 化 則 能 出 矣 。

In reference to the Bladder, it holds the office of Administrator and Chief. The thin (day) and thick (night) fluids (humors) are stored there. That which has been transformed by the Qi can emerge from it.

The Bladder meridian runs up and down either side of the spine, containing in it’s acupuncture points a pool of qi for each organ system, and even points for some areas of the body that weren’t recognized as organs during Classical Chinese times. As can be seen by the character Zhou, 州, meaning “prefecture,” there are islands within the water. Perhaps this visualization can point towards the Bladder’s administrative functions of containing these important points within it’s meridian.
The character, 都, is composed of the radical for “cooking in a pot” and a “flag.” This could be translated as “capital,” but the latin root of this word has the meaning of “head.” Capital is the top of a columnar pole, and the word can also refer to the chief of a tribe. The Bladder meridian literally flows over the top of the head, before running down the back. It serves a protective role in it’s Taiyang correspondence.
The Bladder heads up the other organs, in it’s protective role, and serves an administrative role by organizing the body’s energies in such a way that they can be easily and meaningfully accessed down it’s territory.