What effect do constrained airways have upon velocity, when the ventilation pressure remains constant?

When ventilation pressure remains constant in a system with constrained or narrowed airways, the velocity of airflow is decreased. This phenomenon is explained by the principle of continuity in fluid dynamics, which explains that when the diameter of a conduit (in this case, the airway) is reduced, the flow must compensate for the decrease in cross-sectional area to maintain a given flow rate.

According to the Bernoulli’s principle and the continuity equation, when airflow passes through a constriction, its speed must be inversely proportional to the area of the airway. As the area decreases due to constriction, the air's velocity decreases if the overall pressure is held constant. In addition, factors such as resistance also increase as the airway becomes more constricted, further contributing to the reduction in velocity under the same pressure conditions.

Understanding airflow dynamics is crucial in various practical applications, such as in respiratory therapy or understanding certain medical conditions affecting breathing, where airway diameter plays a vital role in airflow rates.