ANATOMY

Detailed explanation-1: -10, 40, 41 The parasympathetic nervous system also has a role in reflex bronchoconstriction42 and it is generally accepted that this effect is exaggerated in asthmatics, causing a hyper-responsiveness to cold air, rapid breathing, sulphur dioxide, citric acid and histamine.

Detailed explanation-2: -The parasympathetic nervous system is the dominant neuronal pathway in the control of airway smooth muscle tone. Stimulation of cholinergic nerves causes bronchoconstriction, mucus secretion, and bronchial vasodilation.

Detailed explanation-3: -Asthma is associated with autonomic nervous imbalance: an increased bronchial sensitivity to cholinergic constrictors and possibly a decreased sensitivity to beta2-adrenergic dilators have been reported in this disease.

Detailed explanation-4: -In acute exacerbations of asthma, bronchial smooth muscle contraction (bronchoconstriction) occurs quickly to narrow the airways in response to exposure to a variety of stimuli including allergens or irritants.

Detailed explanation-5: -Mast cells are also important in the pathophysiology of asthma. Activated mast cells release histamine and other inflammatory mediators that cause bronchoconstriction and the recruitment of immune cells to the airway (109).