Basic and Clinical Sciences (BCSE) Practice Exam

The bronchopulmonary segment is the correct answer as it represents a functionally independent unit of lung tissue. Each bronchopulmonary segment is supplied by a single tertiary bronchus, which branches from the main bronchus, and receives a branch of the pulmonary artery that provides the necessary blood supply for gas exchange. This functional separation is crucial for both pulmonary health and clinical considerations, such as surgical resections, because it allows for the removal of one segment without affecting the adjacent segments. Each segment is also encapsulated, which helps contain infections or other pathological conditions. The other structures mentioned do not meet the criteria of receiving both a tertiary bronchus and a branch of the pulmonary artery. Bronchioles are smaller air passages that branch off from the tertiary bronchi and do not directly receive these structures. The lobe of the lung consists of multiple bronchopulmonary segments and serves as a larger anatomical division. On the other hand, alveoli are the microscopic air sacs where gas exchange occurs and are not directly involved in the receipt of bronchial and arterial branches.