Which receptors located in the carotid arteries sense chemical changes and stimulate heart rate when carbon dioxide increases during exercise?

• A. Baroreceptors
• B. Proprioceptors
• C. Chemoreceptors
• D. Adrenaline

Answer: (C)

Chemoreceptors in the carotid bodies monitor arterial blood for chemical changes, especially rising CO2 and a drop in pH that occur during exercise. When they detect these changes, they send signals to the brainstem that increase heart rate via the autonomic system, helping to boost oxygen delivery and carbon dioxide removal. Baroreceptors respond to blood pressure, not chemical changes; proprioceptors sense movement, not chemical status; adrenaline is a hormone, not a receptor in the carotid arteries.