Neuromental factors The inhibitory system of nanc is the major the airway. Su Nstance p the transmitter of the of nervous system that relaxes the smooth muscle stimulative nervous system of nanc. is present in the class c chemosensitive afferent fibers of the vagus. when the class c afferent nerve ending is exposed due to injury of the airway, local lesion might be aggravated. Abrupt change of emotion might induce asthma attack, especially in those with refractory asthmaNeuromental factors The inhibitory system of NANC is the major nervous system that relaxes the smooth muscle of the airway. Substance P, the transmitter of the stimulative nervous system of NANC, is present in the class C chemosensitive afferent fibers of the vagus.when the class C afferent nerve ending is exposed due to injury of the airway, local lesion might be aggravated. Abrupt change of emotion might induce asthma attack, especially in those with refractory asthma