Which respiratory drive responds to changes in carbon dioxide levels in the blood?

Which respiratory drive responds to changes in carbon dioxide levels in the blood?

• A. Ventilatory Drive
• B. Carbonic Drive
• C. Hypoxic Drive
• D. Neural Drive

Answer: (B)

The key idea here is how breathing is controlled by carbon dioxide levels. The drive to breathe that responds specifically to CO2 is the carbon dioxide drive. CO2 easily crosses into the brain, where in the cerebrospinal fluid it forms carbonic acid and then dissociates to hydrogen ions and bicarbonate. The resulting increase in hydrogen ion concentration lowers CSF pH and stimulates central chemoreceptors in the medulla, sending signals to increase ventilation so CO2 is expelled. This central CO2–driven drive is the primary regulator of normal breathing. In contrast, a hypoxic drive responds to low oxygen levels, and vent or neural drive are more general terms that don’t pinpoint the CO2-sensing mechanism.

The key idea here is how breathing is controlled by carbon dioxide levels. The drive to breathe that responds specifically to CO2 is the carbon dioxide drive. CO2 easily crosses into the brain, where in the cerebrospinal fluid it forms carbonic acid and then dissociates to hydrogen ions and bicarbonate. The resulting increase in hydrogen ion concentration lowers CSF pH and stimulates central chemoreceptors in the medulla, sending signals to increase ventilation so CO2 is expelled. This central CO2–driven drive is the primary regulator of normal breathing. In contrast, a hypoxic drive responds to low oxygen levels, and vent or neural drive are more general terms that don’t pinpoint the CO2-sensing mechanism.