Step-by-step explanation:
The constriction of tracheal smooth muscle is primarily regulated by the autonomic nervous system. The parasympathetic nervous system, through the release of acetylcholine, is responsible for stimulating the contraction (constriction) of tracheal smooth muscle. This constriction is a part of the body's natural response to various stimuli, such as irritants or allergens in the air, and it can lead to airway narrowing.
Conversely, the sympathetic nervous system, through the release of norepinephrine, has the opposite effect and can relax the smooth muscle in the trachea, leading to airway dilation.
These mechanisms play a crucial role in regulating airflow and maintaining appropriate airway size and tone.