Which concept are central chemoreceptors primarily sensitive to?

• A. Oxygen levels
• B. CO2/pH changes
• C. Temperature fluctuations
• D. Nitrogen levels

Answer: (B)

Central chemoreceptors are primarily sensitive to changes in carbon dioxide levels and pH in the cerebrospinal fluid. These receptors are located in the medulla oblongata of the brain and play a crucial role in the regulation of respiratory rate and depth. When carbon dioxide levels in the blood increase, it diffuses into the cerebrospinal fluid, causing a decrease in pH (making it more acidic). This change is detected by the central chemoreceptors, which then signal the respiratory centers to increase ventilation to exhale more carbon dioxide, thereby helping to restore normal pH levels and maintain homeostasis.

The sensitivity of central chemoreceptors specifically to CO2 and pH changes highlights their function in monitoring the body's metabolic status and ensuring adequate gas exchange, as opposed to other factors like oxygen levels, temperature fluctuations, or nitrogen levels, which are more closely monitored by peripheral chemoreceptors or are not directly influential in respiratory control at the central level.