The large intestine generally includes the cecum, colon and rectum, and the colon includes the ascending colon, transverse colon and descending colon. The function of the large intestine is to absorb water and electrolytes, form storage and excrete feces, and the general absorption of water and sodium is mainly done in the colon. The descending colon and sigmoid colon also absorb water, but their main function is to store and excrete feces. In addition to the functions of storing and excreting feces and absorbing water, sodium and electrolytes, the colon also secretes mucus, which can be attached to the intestinal wall to protect it from bacterial infection and prevent some mechanical damage to the intestinal wall, and the secreted mucus can promote the excretion of feces.