The large intestine is connected with the small intestine in the upper and the anus in the lower. The physiological function of the large intestine is mainly to receive the waste of food transmitted down from the small intestine. After absorbing part of the water in it, the large intestine transmits the waste downward and transforms it into stool to be excreted from the anus.
The function of the large intestine to transmit the waste of food is described in Huangdi Neijing as "transmission and excretion", the activities of which are accomplished by the propelling function of the large intestinal qi. If the large intestine is abnormal in function, it will lead to constipation due to improper transmission and diarrhea due to insufficient absorption of water.