NREMT Paramedic Practice

Which of the following mechanisms primarily regulates pH levels in the body?

1. Respiratory control

2. Renal control

3. Hematologic control

4. Neurological control

The correct answer is: Respiratory control

The primary mechanism for regulating pH levels in the body is respiratory control. This process involves the regulation of carbon dioxide (CO2) levels in the blood, which directly impacts acidity. When CO2 is produced in the body, it reacts with water to form carbonic acid, which dissociates into hydrogen ions and bicarbonate, leading to a decrease in pH (more acidic). The respiratory system adjusts the rate and depth of breathing to either retain or expel CO2. If the body experiences an increase in acidity (lower pH), such as during metabolic acidosis, the respiratory rate increases to blow off more CO2, helping to raise the pH back to normal. Conversely, if the body is too alkaline (higher pH), the respiratory rate decreases, allowing CO2 to accumulate and thus lower the pH. This respiratory control can affect pH rapidly, usually within minutes, making it a primary regulator of blood pH. While renal control also plays a significant role in long-term pH regulation by adjusting the excretion or reabsorption of hydrogen and bicarbonate ions, it operates over a slower timescale, typically requiring hours to days to have a significant effect. Hematologic and neurological controls do not primarily