What is bronchoconstriction?

• A. Narrowing of air passages
• B. Expansion of air passages
• C. Increased airflow to the lungs
• D. Decrease in lung capacity

Answer: (A)

Bronchoconstriction refers to the narrowing of the air passages in the respiratory system, specifically the bronchi and bronchioles. This process occurs when the smooth muscles surrounding the airways contract, leading to a reduced diameter of the air passages. As a result, airflow to and from the lungs is impeded, which can cause difficulty in breathing and is often seen in conditions such as asthma and certain allergic responses.

In contrast, the other options describe opposite or irrelevant physiological actions. Expansion of air passages would indicate bronchodilation, which increases airflow and is beneficial in improving breathing. Increased airflow to the lungs is an outcome of bronchodilation and not bronchoconstriction. A decrease in lung capacity relates to overall lung mechanics and may be influenced by a variety of factors including respiratory diseases, rather than directly describing the action of bronchoconstriction itself. Therefore, narrowing of air passages is the definitive characteristic of bronchoconstriction, aligning with the correct answer.