Physiological dead space can be described as which of the following?

Physiological dead space can be described as which of the following?

• A. From the nares to the bronchioles and includes the volume of air in the alveoli that cannot participate in gas exchange.
• B. From the alveolar sacs to the alveoli that do not participate in gas exchange.
• C. From the nares to the bronchioles and includes the volume of air in the alveoli that participates in gas exchange.
• D. Only alveolar air participates in gas exchange.

Answer: (C)

Physiological dead space is the portion of each breath that does not participate in gas exchange. It combines anatomical dead space—the airways from the nose down to the bronchioles where no gas exchange occurs—with alveolar dead space, which are ventilated alveoli that are not perfused and therefore do not exchange gases. Therefore the description that spans from the nares to the bronchioles and includes air in alveoli that do not participate in gas exchange best captures this concept. Air that does participate in gas exchange is not dead space, and options that imply the opposite or misstate the location are not accurate.

Physiological dead space is the portion of each breath that does not participate in gas exchange. It combines anatomical dead space—the airways from the nose down to the bronchioles where no gas exchange occurs—with alveolar dead space, which are ventilated alveoli that are not perfused and therefore do not exchange gases. Therefore the description that spans from the nares to the bronchioles and includes air in alveoli that do not participate in gas exchange best captures this concept. Air that does participate in gas exchange is not dead space, and options that imply the opposite or misstate the location are not accurate.