GROSS ANATOMY

Detailed explanation-1: -Contraction of the smooth muscle causes bronchoconstriction, decreasing the airway radius. Relaxation of the smooth muscle allows bronchodilation. Airway smooth muscle is under the control of the autonomic nervous system.

Detailed explanation-2: -Bronchoconstriction is one of the hallmarks of asthma. Stimulation of 2 receptors in bronchial smooth muscle results in relaxation of bronchial smooth muscle. This results in a larger diameter airway, resulting in lower resistance to airflow in and out of the lungs (Figure 24-1).

Detailed explanation-3: -A decrease in diameter is called bronchoconstriction, which is the tightening of the smooth muscle surrounding the bronchi and bronchioles due to and stimulated by histamine, parasympathetic nerves, cold air, chemical irritants, excess mucus production, viral infections, and other factors to decrease air flow.

Detailed explanation-4: -Bronchoconstriction is a tightening of smooth muscle surrounding the bronchi and bronchioles with consequent wheezing and shortness of breath.