Small intestine

Abbreviation: SI. The part of the digestive tract joined to stomach at its upper extremity, and the large intestine at the lower extremity; one of the six bowels. The small intestine stands in exterior-interior relationship with the heart. Like the heart, it belongs to fire among the five phases. It has the function of further processing the food already decomposed by the stomach. There are two aspects to this function: reception and holding and transforming matter on the one hand and separating the clear and turbid on the other.

Small Intestine Functions

The Small Intestine Governs Reception and Holding (小肠主受盛 xiǎo cháng zhǔ shòu chéng); the Small Intestine Governs Transformation of Matter (小肠主化物 xiǎo cháng zhǔ huà wù)

The small intestine receives food that has undergone preliminary digestion in the stomach and holds it while it performs further transformation. Sù Wèn (Chapter 8) expresses this as, The small intestine holds the office of Reception; it is responsible for transforming matter (小肠者, 受盛之官也, 化物出焉 xiǎo cháng zhě, shòu chéng zhī guān yě, huà wù chū yān). Disturbance of the function of reception usually leads to qì stagnation and impaired digestion, which manifests in abdominal pain, diarrhea, and sloppy stool. However, this is generally considered a manifestation of spleen-stomach upbearing and downbearing and is therefore treated through the stomach and spleen. In other words, the small intestine’s transformation function is essentially considered as falling within the realm of the stomach and spleen. In most discussions about digestion of food and assimilation of nutrients, the small intestine is not mentioned.

The Small Intestine Separates the Clear and Turbid (小肠主分别清浊 xiǎo cháng zhǔ fēn bié qīng zhuó)

The clear refers to the essence of grain and water, that is, the nutrients contained in food, while the turbid denotes waste. The small intestine extracts the clear, which is absorbed into the body by the action of the spleen. The liquid part of the remaining waste is drawn off and sent to the kidney, while the solid part is passed on to the large intestine. Because the separation of the clear and turbid involves the extraction of a considerable amount of fluid, it is also said that the small intestine governs humor.

When heart fire spreads heat to the small intestine, the function of separating the clear and turbid is disturbed, causing reddish urine and inhibited urination.

The Small Intestine Channel (小肠经 xiǎo cháng jīng)

The small intestine is associated with the hand greater yáng (tài yáng) small intestine channel.

Small Intestine Patterns

For fuller information than is given below, follow the link. See also heart pattern identification.

Small intestine repletion heat (小肠实热 xiǎo cháng shí rè): A repletion pattern marked by heart vexation; heart palpitation; mouth and tongue sores; rough voidings of reddish urine with scorching pain on urination; and in some cases bloody urine. It usually arises when heart fire spreads heat to the small intestine. Less commonly, repletion heat in the small intestine can ascend to affect the heart.