Dictionary of Allergies .. Bronchial irritability

The tendency of the airways to narrow in response to inhaled irritants. The lung, like many other organs, is innervated by a variety of sensory nerves and by nerves of the parasympathetic and sympathetic nervous systems that regulate the function of cells within the respiratory tract. Activation of sensory nerves by both mechanical and chemical stimuli elicits a number of defensive reflexes, including cough, altered breathing pattern, and altered autonomic drive, which are important for normal lung homeostasis. However, diseases that afflict the lung are associated with altered reflexes, resulting in a variety of symptoms, including increased cough, dyspnea, airways obstruction, and bronchial hyperresponsiveness [1].

The irritants may include changes in the physical characteristics of the air breathed, (e.g. its temperature), irritating dusts, and fumes, certain specific chemicals and many substances thought to be responsible for allergy. When an asthmatic is well, and free of wheezing, it is often difficult to demonstrate bronchial irritability in response to physical irritants. However, when an asthmatic become wheezy, for whatever reason then irritability returns. As a symptom, irritability of the airways has been seen to be a hallmark of asthma. Bronchial irritability can also be demonstrated in otherwise healthy persons who develop a chance acute bronchitis due to a virus infection. Bronchial irritability is a striking feature of asthma but it is not exclusive to it.

References

Canning BJ, Spina D. Sensory nerves and airway irritability. Handb Exp Pharmacol. 2009;(194):139-83.