When cholinergic receptors in the airways are stimulated, a series of physiological responses occur that can significantly impact respiratory function. Cholinergic receptors are part of the parasympathetic nervous system, which is responsible for ‘rest and digest’ activities.
In the airways, the stimulation of these receptors, particularly the muscarinic subtype, leads to bronchoconstriction, which is the narrowing of the air passages. This is primarily achieved through the contraction of smooth muscle surrounding the bronchi and bronchioles, which reduces airflow and can lead to difficulty in breathing.
Additionally, cholinergic stimulation increases the secretion of mucus in the airways. This increased mucus production can contribute to airway obstruction, exacerbate conditions such as asthma or chronic obstructive pulmonary disease (COPD), and ultimately impair gas exchange in the lungs.
In summary, stimulation of cholinergic receptors in the airways results in bronchoconstriction and increased mucus secretion, both of which can lead to respiratory distress and impaired lung function.