Which term describes the non-gas-exchanging portion of the respiratory system?

Which term describes the non-gas-exchanging portion of the respiratory system?

• A. Tidal Volume
• B. Alveolar Ventilation
• C. Dead Space in Lungs
• D. Functional Residual Capacity

Answer: (C)

Dead space describes the non-gas-exchanging portion of the respiratory system. It includes anatomical dead space in the conducting airways—air that fills the trachea and bronchi but doesn’t reach the alveoli for gas exchange—and any physiologic dead space where alveoli aren’t effectively participating in exchange. Because of this, only the air that reaches the alveoli contributes to oxygen and carbon dioxide transfer, which is why alveolar ventilation is the portion of each breath that actually participates in gas exchange. Tidal volume is the total air moved in and out each breath, but part of that volume stays in the dead space and doesn’t participate in gas exchange. Functional residual capacity is the volume left in the lungs after a normal exhalation and isn’t specifically the non-gas-exchanging portion.

Dead space describes the non-gas-exchanging portion of the respiratory system. It includes anatomical dead space in the conducting airways—air that fills the trachea and bronchi but doesn’t reach the alveoli for gas exchange—and any physiologic dead space where alveoli aren’t effectively participating in exchange. Because of this, only the air that reaches the alveoli contributes to oxygen and carbon dioxide transfer, which is why alveolar ventilation is the portion of each breath that actually participates in gas exchange. Tidal volume is the total air moved in and out each breath, but part of that volume stays in the dead space and doesn’t participate in gas exchange. Functional residual capacity is the volume left in the lungs after a normal exhalation and isn’t specifically the non-gas-exchanging portion.