Answer :
Final answer:
Significant increases in ventilation are prompted by small increases in arterial CO2 levels due to the sensitivity of central chemoreceptors to blood pH changes, unlike the less immediate response to small decreases in oxygen levels. Hence option B is correct.
Explanation:
Small increases (2-3 mmHg) in arterial PCO2 have a significant effect on increasing ventilation compared to small decreases (i.e., 2-3 mmHg) in PO2. This is because central chemoreceptors in the medulla oblongata are very sensitive to changes in pH, which is influenced by the concentration of CO2 in the blood. When CO2 levels rise above normal, blood pH drops, triggering an increase in the rate and depth of respiration to expel the excess CO2, effectively increasing ventilation. On the other hand, the body's response to decreases in PO2 is less immediate and significant, as it takes a more substantial drop in PO2 levels to elicit a strong respiratory response. Hence option B is correct.
