The Small and Large Intestine in Korean Medicine: Sorting and Discharging
After the spleen and stomach comes the rest of the digestive tract. In Korean Traditional Medicine (KTM), the traditional healing system of Korea also known as Hanbang (한방), the small intestine and large intestine finish the work the stomach began — extracting the last of the food essence, sorting what is useful from what is not, and discharging the remainder. They are Fu, passing-through organs, and this article rounds out the digestive system begun in the companion piece on the spleen and stomach.
In Summary
- The small intestine receives the food the stomach has partly digested, transforms it further, and separates the clear from the turbid — sending the clear essence up (for the spleen to raise) and the residue down to the large intestine.
- The sorting of clear from turbid is shared by the spleen and the small intestine, which are a closely connected pair.
- The large intestine conducts and transforms the residue: it receives what the small intestine has sorted out, absorbs the leftover fluid, and forms stool to be discharged.
- Because the large intestine reclaims fluid, a shortage of Body Fluids is worth checking there too, not only at the kidney, liver, and heart.
- The liver and large intestine are closely linked: when the liver’s coursing of Qi weakens, bowel movement often weakens with it, and conversely intestinal illness can sap the muscle strength the liver governs.
The Small Intestine: Receiving, Transforming, and Separating Clear from Turbid
The small intestine’s work is captured in three terms: receiving, transforming, and separating clear from turbid. It receives (受盛) the food the stomach has roughly digested — it is the vessel that holds it. There the food is digested further and its essence absorbed, which the spleen then transforms and raises, while the remaining matter is passed down to the large intestine; this is transforming food (化物). And as that happens, the clear and the turbid are separated (淸濁의 비별): the clear part — the essence — rises, and the turbid residue goes down to the large intestine.
Drawing the clear essence out of food and parting it from the turbid is a function shared by the spleen and the small intestine. In the relationships among organs, the spleen and small intestine are a connected pair, and that connection matters in disease: trouble in one readily shows up in the other.
The Large Intestine: Conduction and Transformation
The large intestine governs conduction and transformation. It receives the residue the small intestine has sorted off, absorbs the surplus fluid from it, and forms stool to send out of the body. Classically it is called the organ of conduction, the place from which “transformation issues” — the turning of food into stool being that transformation.
One clinical note follows from its fluid work. Because the large intestine reclaims leftover fluid, a problem of insufficient Body Fluids is usually approached through the kidney, liver, and heart — but the large intestine deserves a look as well, since fluid lost or poorly reclaimed here is part of the same picture.
The Liver and Large Intestine
The large intestine is tied closely to the liver. When the liver’s coursing of Qi declines, the large intestine’s conducting function — that is, bowel movement — often declines with it. The link runs the other way too: when the large intestine is ill, the muscle function the liver governs can weaken. Anyone who has felt their strength drain out of their muscles after a bout of severe diarrhea has felt this connection directly. (Why exactly the liver and large intestine communicate is a thread taken up elsewhere.)
In Summary
The small and large intestine complete the digestive tract. The small intestine receives the stomach’s output, transforms it, and separates the clear essence (sent up via the spleen) from the turbid residue (sent down) — a sorting it shares with the spleen. The large intestine conducts that residue, reclaims its leftover fluid, and forms stool, which is also why it bears on Body-Fluid shortage; and it stands in a close, two-way relationship with the liver. With the digestive tract complete, the organ series moves on.
Related reading: The Spleen and Stomach in Korean Medicine · The Organs in Korean Medicine
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.
