The large intestine meridian communicates with the lung (肺), with which it is externally-internally related.
The two paired organs are associated with the metal element (金) and the emotion of grief.
Pathological changes of the large intestine will lead to dysfunction in this transportation function, resulting in loose stools and constipation.
[1] Large intestinal disease (dà cháng bìng) is attributable to evils such as heat, cold, stagnation, dampness, and wind, or to vacuity.
Rumbling intestines or pain around the umbilicus, constipation or diarrhea, bloody stool or tenesmus with blood and pus in the stool, and prolapse of the rectum are signs of large intestine disease.