What occurs when there is an increase in hydrogen ion concentration detected by central chemoreceptors?

• A. Hyperventilation
• B. Bradypnea
• C. Hypoventilation
• D. Apnea

Answer: (A)

An increase in hydrogen ion concentration in the blood, which indicates a drop in pH (acidosis), is primarily detected by central chemoreceptors located in the medulla oblongata of the brain. These chemoreceptors play a crucial role in regulating respiratory patterns.

When hydrogen ion concentration rises, the central chemoreceptors stimulate an increase in the rate and depth of ventilation—this physiological response is known as hyperventilation. The rationale behind this is that by increasing ventilation, the body can expel more carbon dioxide (CO2), which in turn helps to raise the pH back towards normal levels. This compensatory mechanism is vital in maintaining acid-base homeostasis.

Given this understanding, the correct answer reflects the necessary response of the respiratory system to counteract the effects of acidosis indicated by the increase in hydrogen ions.