Question

Which structures of the lower respiratory system primarily alter airway resistance due to their smooth muscle component?

a) Bronchi
b) Alveoli
c) Trachea
d) Bronchioles

Answer 1

The bronchioles are the structures in the lower respiratory system that primarily alter airway resistance due to their smooth muscle component, managing airflow with contractions.

Step-by-step explanation:

The structures of the lower respiratory system that primarily alter airway resistance due to their smooth muscle component are d) Bronchioles. The bronchioles are smaller passages that branch off from the tertiary bronchi and feature a significant amount of smooth muscle relative to their size, which can contract or relax to regulate airflow. These structures lack the cartilaginous support found in larger airways, such as the bronchi, making the role of smooth muscle critical in controlling resistance and maintaining the airway's shape during the breathing process.