Reddened and inflamed mucosa
In acute bronchitis, and in response to prolonged coughing, it is possible that the cells in the bronchial lining get irritated. Thus, the mucous membrane start looking reddened and inflamed because of increased blood flow towards the inflamed site. This inflammation leads to impaired function of the bronchial lining, which is responsible for clearance of the irritants that comes along the airway. Sometimes, the reddened area extends to your throat, in which case it will be necessary to rule out pharyngitis, too.