There is very little to no sympathetic *innervation* of the smooth muscle in the respiratory tract. The only form of sympathetic action that we could speak of for the smooth muscles of the respiratory system is an increase in circulating catecholamines via sympathetic stimulation of the adrenal gland. In normal physiologic conditions, the parasympathetic system is the primary modulator of airway smooth muscle tone, with bronchodilation usually being achieved by dampening the parasympathetic activation and decreasing bronchoconstriction. This is a key difference between the sympathetic and parasympathetic systems with regards to the respiratory system, as the parasympathetic system directly innervates airway smooth muscle while the sympathetic system does not. I tried to adjust the card to fit given this but it might just need to be removed.
Ref: Reflex regulation of airway smooth muscle tone, Brendan J. Canning, Journal of Applied Physiology 2006 101:3, 971-985
Quoting from the abstract: "Sympathetic-adrenergic innervation of human airway smooth muscle is sparse or nonexistent based on histological analyses and plays little or no role in regulating airway caliber."
