instruction: hello doctor I have a cough at certain times almost every day due to post nasal drip I take allergy medication cetirizine but it does not seem to help I have tried other techniques like lavage and have tried thinning my mucus by drinking more water as advised by all the medical web sites all the explanations I read online say that post nasal drip is caused by a thickening of the mucus that the mucus membranes make about a quart a day of mucus which normally is thin enough to slide down the throat unnoticed and ends up in the stomach but if it is too thick it is noticeable and it ends up going down the windpipe and needs to be brought up through coughing here is what I do not understand normally the passage that is open is the trachea the epiglottis only closes when swallowing and furthermore it is behind the esophagus so why the thin mucus which is sliding down our throat unnoticed does not go down into our lungs it makes no sense if I do not notice it and thus do not consciously swallow it how does it go down the esophagus it should be the opposite please suggest
output: hi I am so delighted to read your query my initial thoughts were that you were kidding but when I thought I realized how beautifully you have thought about the question we need to know about mucociliary clearance direction of mucus movement closure of airway by the epiglottis supraglottis and by the glottis mucociliary movement occurs towards the throat and that is what brings the mucus towards the throat like you said when the mucus gets thick due to allergy or infection or rhinitis one gets a feeling of the movement cilia are small brush like extensions from cells which beat in a particular direction so as to drive the mucus film over the cilia towards the throat from the throat the brush border epithelium that is the ciliated columnar respiratory epithelium pushes the mucus towards the pyeariform fossa preferentially the epiglottis and aryepiglottic fold and the inter arytenoid region form the supraglottic closure which acts as the first check point towards aspirating one own saliva the next check point is the glottis or the vocal cords which remain closed to prevent aspiration in such times when the mucus drip is constant and thick then some microaspirations occur due to the nature of the mucus as well as due to any lax behavior of the closures causing some cough or chest infection you must understand that the vocal cords trachea and the respiratory pathways further below are also lined by ciliated epithelium which also have a mucus layer on top of them this mucus layer traps smaller particles which escape the upper airways and bring them away from alveoli they also moisturize the air we inhale in your case you need to arrest the cause that is causing the thick mucus that is inside the nose you need a asteroidal nasal spray taken in a particular way for a few weeks this supplemented with an antacid like protonic and cetrizine will provide you lasting relief you should also take mucolite for a few days to lighten the mucus couple this with steam and plenty of water avoid exposure to sun smoke pollution and dust