Tachypnea may occur in response to which condition?

• A. Decreased metabolic rate
• B. An increased metabolic rate
• C. Stable metabolic rate
• D. Hypotension

Answer: (B)

When metabolic activity rises, tissues use more oxygen and produce more carbon dioxide. The body responds by increasing ventilation to remove the extra CO2 and bring in O2, so breathing becomes faster and shallower—tachypnea. This rate adjustment is driven by chemoreceptors sensing CO2 and pH changes in the blood and by the need to match oxygen delivery to demand.

So an increased metabolic rate directly leads to tachypnea as the respiratory system works harder to balance gas exchange. Decreased or stable metabolic rate doesn’t create the same drive to ventilate more, and hypotension affects circulation more than it does the immediate need to increase breathing rate.