**Question:** All of the following are characteristic of a bronchopulmonary segment, except:

A. Consists of a single bronchus
B. Encloses an entire lobe
C. Has its own pleura and fissure
D. Is supplied by two pulmonary arteries

**Core Concept:** A bronchopulmonary segment is a functional unit of the lung, which is composed of a bronchus, its associated lung parenchyma, and the pleura that covers it. Segments are subdivisions of lobes and are essential for understanding anatomy, surgical procedures, and lung diseases.

**Why the Correct Answer is Right:** Option D is correct because a bronchopulmonary segment is supplied by a single pulmonary artery, not two. Each segment receives its blood supply from a single branch of the pulmonary artery, which enters the segment through the hilum and divides into two or three branches.

**Why Each Wrong Option is Incorrect:**

A. **Consists of a single bronchus**: A bronchopulmonary segment contains a bronchus, but it is not characteristically composed of a single bronchus. Segments have multiple bronchi branching off the main bronchus, supplying oxygenated blood to the segment.

B. **Encloses an entire lobe**: A bronchopulmonary segment does not enclose an entire lobe; instead, it is a subdivision of a lobe. A segment is a smaller functional unit than a lobe, which consists of multiple segments.

C. **Has its own pleura and fissure**: A bronchopulmonary segment does have its own pleura (lining of the lungs) but is not explicitly associated with a fissure (a suture line that divides the lung into lobes). A fissure divides a lobe into segments, not segments into lobes.

**Clinical Pearl:** Understanding bronchopulmonary segments is essential for clinical practice, such as during lung biopsy, lobectomy, and segmentectomy procedures. This knowledge helps in identifying, preserving, and performing surgical interventions accurately while preserving lung function.

**Correct Answer:** D (A bronchopulmonary segment receives blood supply from a single pulmonary artery)

**Explanation:** Each bronchopulmonary segment is supplied by a branch of a pulmonary artery, which enters the segment through the hilum and divides into two or three branches. This ensures that the segment receives a sufficient blood supply for gas exchange and tissue oxygenation. The single arterial supply allows for efficient distribution of oxygen and nutrients to the segment while minimizing hypoxia and ischemia within the segment.