The stimulation of sensory nerves that functions as cough receptors involves a complex reflex arc beginning. Primary clinical data suggests that the sensory limb of the reflex exists in and outside of the lower respiratory tract.

Myelinated and rapidly adapting pulmonary stretch receptors (RARs), known as irritant receptors, are the type of sensory nerve stimulating the cough center in the brain, afferent C-fibers. Slow adapting pulmonary stretch receptors (SARs) can also modulate cough. RARS, C-fibers, and SARs are identified in the distal esophageal mucosa but studies are not conducted to determine if they can participate in the cough reflex.

Even though the gastroesophageal reflux disease can stimulate the afferent limb of the cough reflex by irritating the upper respiratory tract (without aspiration) and the lower respiratory tract (by micro- or macroaspiration).

Evidence strongly suggests that reflux irritates cough by stimulating an esophageal-bronchial reflex. The pathways of this reflex may be modeled in a variety of ways in theory. The main role of acid while triggering the cough by this reflex is not known due to the conflicting results from challenging studies. It can be speculated that a distal esophageal-bronchial reflex can be an early warning defense for the coughing to get started, in case the refluxate reaches the inlet of the lower respiratory tract.

Thus, teleologically, an esophageal-bronchial reflex can be evolved as one of the numerous mechanisms to protect the lungs from aspiration of gastric contents.

Source: Irwin RS, Madison JM, Fraire AE. The cough reflex and its relation to gastroesophageal reflux. Am J Med. 2000 Mar 6;108 Suppl 4a:73S-78S. doi: 10.1016/s0002-9343(99)00341-1. PMID: 10718456.