What type of muscle primarily composes the walls of the bronchioles?

The walls of the bronchioles are primarily composed of smooth muscle. This type of muscle is characterized by its involuntary control, meaning it operates without conscious effort, and it is found in various systems throughout the body, including the respiratory system. Smooth muscle allows for the regulation of airway diameter by contracting or relaxing, which plays a crucial role in controlling airflow to the alveoli for gas exchange.

This capacity for regulation is essential, particularly in response to various stimuli such as irritants, allergens, or during episodes of asthma, where bronchoconstriction occurs due to the tightening of smooth muscle. The functionality of bronchioles is largely dependent on this smooth muscle composition.

Other muscle types, such as skeletal and cardiac muscle, are not found in the bronchioles. Skeletal muscle is responsible for voluntary movements and is attached to bones, while cardiac muscle makes up the heart and is specialized for continuous involuntary contractions. Connective tissue serves a different function, providing support and insulation, but does not in itself contribute to the functional dynamics of bronchioles. Thus, smooth muscle is essential for the proper functioning of the bronchioles in the respiratory system.