Anatomy of the Respiratory System Quiz

• A The right lung has three lobes and the left lung has two lobes ✓
• B Both lungs have two lobes separated by oblique fissures only
• C The right lung has two lobes and the left lung has three lobes
• D The number of lobes is the same as the number of bronchopulmonary segments
• E Both lungs have three lobes separated by horizontal fissures

Explanation

Why A is correct

See The Thoracic Cavity. Option A is correct. The right and left lungs are not mirror images. The right lung has three lobes (superior, middle and inferior) separated by two fissures: an oblique fissure and a horizontal fissure (a fissure is a deep groove in the lung surface that separates the lobes). The left lung has two lobes (superior and inferior), separated by a single oblique fissure. The left lung has a deep indentation on its front edge, called the cardiac notch, which is made by the heart. Within each lobe the lung is divided into bronchopulmonary segments: each segment is supplied by its own segmental bronchus (a small branch of the airway tree) and is a functional unit of the lung. A simple memory aid: right has three lobes, left has two.

• Right lung: Three lobes, separated by an oblique and a horizontal fissure.
• Left lung: Two lobes, separated by a single oblique fissure.
• Left lung notch: The cardiac notch is made by the heart.

Why the other options are incorrect

• B. Both lungs have two lobes separated by oblique fissures only: This is true only of the left lung. The right lung has three lobes, divided by an oblique and a horizontal fissure.
• C. The right lung has two lobes and the left lung has three lobes: This reverses the true arrangement. The right lung is the one with three lobes, and the left lung has two.
• D. The number of lobes is the same as the number of bronchopulmonary segments: Each lobe is divided into several bronchopulmonary segments, the functional units of the lung, so the segments are more numerous than the lobes.
• E. Both lungs have three lobes separated by horizontal fissures: Only the right lung has three lobes and a horizontal fissure. The left lung has two lobes separated by a single oblique fissure.

Easy

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