Why can pulmonary embolisms cause a V/Q mismatch?

Pulmonary embolisms cause a V/Q mismatch primarily because they block pulmonary arterial blood flow. When a pulmonary embolism occurs, a blood clot or obstruction travels to one or more pulmonary arteries in the lungs, impeding blood flow to the affected areas. This obstruction means that although air can reach the alveoli (where gas exchange occurs), the necessary blood flow to facilitate the exchange of gases (oxygen and carbon dioxide) is reduced or absent.

In a normal functioning respiratory system, both ventilation (the amount of air getting to the alveoli) and perfusion (the amount of blood reaching the alveoli) must be matched for efficient gas exchange. However, with a pulmonary embolism, while ventilation remains intact in the areas where blood flow is obstructed, the perfusion is compromised. This leads to areas of the lung being ventilated but not perfused, creating a situation known as a ventilation/perfusion (V/Q) mismatch.

In the context of the other options related to bronchial and bronchiole airflow, these do not directly relate to the mechanism of pulmonary embolism impacts. The key factor in understanding V/Q mismatch in this scenario is the interruption of blood flow within the pulmonary arteries specifically, which makes the correct answer focus on