alleryStart learning →Where does the respiratory zone of the lung begin?
AWhere the tertiary bronchus enters a lobule
BWhere the trachea divides into two bronchi
CWhere a terminal bronchiole meets a respiratory one
DWhere alveolar sacs open into alveolar ducts
Answer & Solution
Correct answer: C. Where a terminal bronchiole meets a respiratory one
1. The respiratory zone is defined by direct involvement in gas exchange.
2. It begins where terminal bronchioles join a respiratory bronchiole, the smallest type of bronchiole.
3. The respiratory bronchiole then leads to an alveolar duct opening into a cluster of alveoli.
4. The trachea and tertiary bronchi are conducting structures, so the first two options sit too high in the tree.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 22 "The Respiratory System", section 22.1 Organs and Structures of the Respiratory System_
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