The lung governs depuration and descent while the large intestine controls transmission. Normal function the lung will transmit fluid downward to moisten the large intestine and promote the transmission of the large intestine. Normal function of the large intestine will ensure smoothness of the large intestinal qi and promote depuration and descent of lung-qi. 

So physiologically the lung and the large intestine depend on each other. Pathologically, failure of the lung to depurate and descend and failure of the large intestine to transmit will affect each other, bringing on various symptoms due to disorder of both the lung and the large intestine, such as chest oppression, cough, retention of dry feces or constipation.