Which process describes widening of the air passages in the lungs, often facilitated by beta-agonists?

• A. Bronchoconstriction
• B. Inflammation
• C. Bronchodilation
• D. Respiratory distress

Answer: (C)

Bronchodilation is the widening of the air passages in the lungs. When beta-agonist drugs bind to beta-2 receptors on airway smooth muscle, they trigger a signaling cascade that increases cyclic AMP, causing the smooth muscle to relax. This relaxation relaxes the bronchi and bronchioles, expanding the lumen and making it easier for air to flow in and out. That’s why this term best describes the process described in the question. Bronchoconstriction would narrow the airways, inflammation can contribute to narrowing but is not the widening process, and respiratory distress is a clinical condition rather than a specific mechanism.