The Organs in Korean Medicine: Zang, Fu, and the Extraordinary Organs

Having covered the three substances — Qi, Blood, and Body Fluids — the foundation of Korean Traditional Medicine (KTM), the traditional healing system of Korea also known as Hanbang (한방), turns next to the organs. The word for the organs (臟腑, jang-bu) names all the internal organs together. The basic division is into two — the storing Zang and the passing-through Fu — and within the Fu sits a special, exceptional set, the extraordinary organs. This article lays out that scheme, and dwells on the extraordinary organs, which are the least familiar part of it.

The Two Basic Classes: Zang and Fu

The internal organs divide first into two. The Zang (臟) carry the sense of storing; the Fu (腑) carry the sense of a warehouse — a place things enter and leave without staying. The relationship between them is best understood as one of role. The Zang take the leading, active part in the body’s functioning: they are the producers, where the body’s work originates. The Fu carry out the downstream task — moving onward, and discharging, the material that results from the Zang’s activity.

The contents of each follow from that role. Because the Zang exist to store, they are filled with yin-essence — the refined, yin substances of essence, Blood, and Body Fluids — and not with the coarse, undigested matter of food. The Fu are the reverse: full of that coarse, moving matter, but not of stored essence. Hence one of the most quoted rules in KTM physiology: the Zang are healthy when they are full, and the Fu are healthy when they are empty. (This filling-and-emptying rhythm, and how it underlies the constitutions, has its own dedicated article.) Underneath this sits a useful point: the Zang do not store Qi as Qi. Each Zang takes up the Qi that matches its nature and, by the principle that accumulated Qi forms substance, gathers it into stored material form — the yin-essence it holds.

Within the Fu: The Six Fu and the Extraordinary Fu

The Fu are not all alike. The ordinary six Fu are what we usually mean by “Fu” — organs through which food-type material flows and is passed on, with nothing lodging for long. The extraordinary organs (奇恒之府, the “extraordinary Fu”) belong to the Fu as well, hollow in form like the rest — but they are exceptional, and the name says exactly that.

The decisive difference is what fills them. Through the six Fu flows food and its residue. Into the extraordinary Fu comes something altogether different: the product of the five Zang’s activity. And instead of passing that product straight on, as an ordinary Fu would, the extraordinary Fu keep it in reserve and draw on it only when the body has need of it. They are, in short, Fu in form that store and release on demand — formed, in classical terms, from the yin Qi of the earth, and, like the earth that quietly grows all things, holding their contents in reserve and giving them out as they are needed.

The Extraordinary Organs and Their Zang

The extraordinary organs are the brain, the marrow, the bone, the vessels, the gallbladder, and the uterus. Each stores the product of a particular Zang’s activity: the brain, marrow, and bone hold what the kidney produces; the vessels, what the heart produces; the gallbladder, what the liver produces; and the uterus, what the liver and kidney produce together. The picture to hold is this — the Zang lead and produce, and where their product is something the Zang cannot conveniently keep itself, an extraordinary Fu stores it on the Zang’s behalf, ready to supply it when it is called for.

Two notes round this out. The gallbladder appears twice in KTM — once among the ordinary six Fu and once among the extraordinary organs — because it both moves like a Fu and stores a clear, essence-like fluid like a Zang. And the brain’s place here connects to a point made elsewhere on this site: the brain is an organ in KTM, but as an extraordinary Fu that stores and consumes rather than generating Qi, which is why it is not one of the five Zang on which the constitutions are built.

In Summary

Korean medicine divides the organs into the storing Zang and the passing-through Fu. The Zang take the leading, producing role and are healthy when full; the Fu carry the resulting material onward and out, and are healthy when empty. Within the Fu, the ordinary six pass food-type matter through, while the extraordinary Fu — brain, marrow, bone, vessels, gallbladder, and uterus — are filled instead by the products of the five Zang, storing them in reserve and giving them out only as needed, each paired with the Zang it serves. With this map of the organs in hand, the individual organs — beginning with the heart — come next.

Related reading: Filling Organs vs. Emptying Organs · Why the Brain Is Not One of the Eight

This article reflects the clinical observations and teaching practice of Professor Seungho Baek, Professor of Korean Medicine at Dongguk University College of Korean Medicine, specializing in Pathology and Oncology.