What is the role of chemoreceptors in exercise responses?

• A. They monitor temperature.
• B. They decrease ventilation during exercise.
• C. Chemoreceptors provide feedback to optimize respiratory and cardiovascular responses during exercise, increasing ventilation and cardiac output.
• D. They do not influence exercise responses.

Answer: (C)

Chemoreceptors detect chemical changes in the blood, especially CO2 levels, pH, and, to a lesser extent, O2. During exercise, rising CO2 and H+ (lower pH) signals indicate increased metabolic activity. In response, chemoreceptors inform the brainstem to increase ventilation, helping remove CO2 and maintain pH while also supporting the delivery of more O2 to working muscles. They also influence the cardiovascular system by boosting sympathetic drive, which raises heart rate and stroke volume to increase cardiac output. This together tunes both breathing and blood flow to match the higher energy demand of exercise. They do not monitor temperature, and they do not decrease ventilation; they actively promote ventilation and help optimize the overall exercise response.