Located in the Lower abdomen, the Large Intestine connects at its upper end with the Small Intestine at the ileocecal junction, and at its Lower end with the anus. Meridians connect the Large Intestine with Fei, and thus the two viscera are externally–internally related. The Large Intestine receives digested food and water from the Small Intestine, absorbs additional water, and excretes the stools. The Basic Questions says, “The Large Intestine is the official in charge of transmitting and excreting”. These activities are accomplished by the propelling Qi of the Large Intestine.
If the Large Intestine malfunctions, information regarding the pathological changes in the quantity and quality of feces, and the frequency of defecation, is important for diagnosis. Pi regulates the transformation and transportation of food and water through the digestive system, including the Small and Large Intestines. Treatment of constipation should involve both Fei and the Large Intestine.
The physiological functions of the large intestine
(1) The large intestine relates to Fei
TCM only briefly describes the Large Intestine because it attributes many diseases, such as diarrhea, abdominal distension and pain, to Pi . This is different from CWM, which attributes those illnesses to the Large Intestine only.
(2) Fei and the Large Intestine connect externally–internally through their meridians
Physiologically, Fei’s descending action prompts the Large Intestine to excrete the body’s moistened waste. Large Intestine Fire disturbs Fei –Qi’s descent, and manifests as chest heaviness, cough with constipation, and dyspnea. If inadequate Fei –Qi descends, it will present as difficult defecation.