Basic and Clinical Sciences (BCSE) Practice Exam

What defines a bronchopulmonary segment?

1. Smallest subdivision of a lung

2. Largest subdivision of a lobe of the lung

3. The functional unit of the lung

4. Area of the lung devoid of blood vessels

The correct answer is: Largest subdivision of a lobe of the lung

A bronchopulmonary segment is defined as a distinct anatomical region of the lung that serves as the smallest functional unit. Each segment contains its own air supply through a tertiary bronchus, pulmonary blood supply, and lymphatic drainage. This makes the segment a self-sufficient unit of lung tissue that can be surgically resected if necessary, as its structures are well defined and separated from adjacent segments by connective tissue. The concept of the bronchopulmonary segment being the largest subdivision of a lobe of the lung is more nuanced. While it is true that a lobe is comprised of multiple bronchopulmonary segments, each segment is importantly defined as a unique subsection with independent vascular and bronchial supply. Therefore, while the answer that identifies the bronchopulmonary segment as the largest subdivision of a lobe is technically accurate because it highlights its macroscopic significance, it is essential to understand that it also functions as the smallest anatomical unit that retains independent airway and vascular structures. The other choices, such as the smallest subdivision of a lung, could refer to alveoli or other classifications within the pulmonary structure that do not encapsulate the self-sufficient characteristics of the bronchopulmonary segment. The label of the segment as the functional unit can