What happens to the amount of smooth muscle found in the walls of the respiratory tract as it moves down from the upper conducting zone to the lower respiratory zone?

Question

Quizplus · Accepted Answer

As the respiratory tract moves from the upper conducting zone to the lower respiratory zone, the amount of smooth muscle decreases. This is because the lower respiratory zone, which includes the alveoli, requires less structural support and more flexibility for gas exchange.

What Happens to the Amount of Smooth Muscle Found in the Walls