You are nervous about the third lab exam and the class so you begin to hyperventilate. Which of the following would you expect your acid base status to be? a. metabolic acidosis b. metabolic alkalosis c. respiratory acidosis d. respiratory alkalosis e. none of the above
The correct answer and explanation is:
The correct answer is d. respiratory alkalosis.
Hyperventilation, which is rapid or shallow breathing, occurs when the body expels more carbon dioxide (CO₂) than normal. CO₂ is an acidic compound in the blood, and its rapid removal causes a decrease in the concentration of carbonic acid (H₂CO₃), which leads to an increase in blood pH. This results in respiratory alkalosis, a condition where the blood becomes more alkaline due to excessive exhalation of CO₂.
When the body is stressed, nervous, or anxious, the autonomic nervous system triggers a “fight or flight” response. This response causes increased respiratory rate (hyperventilation), which accelerates CO₂ loss. As the concentration of CO₂ falls, the blood’s pH increases, leading to respiratory alkalosis.
In respiratory alkalosis, the bicarbonate buffer system tries to compensate for the drop in CO₂ levels by reducing the amount of bicarbonate (HCO₃-) in the blood to stabilize pH. However, this compensatory mechanism is slower than the rapid change caused by hyperventilation.
The opposite of respiratory alkalosis, respiratory acidosis, would occur if ventilation were insufficient (e.g., due to obstruction or shallow breathing), causing CO₂ to accumulate in the blood.
In contrast, metabolic acidosis and metabolic alkalosis are conditions where the acid-base imbalance arises from factors unrelated to CO₂ levels. For instance, metabolic acidosis results from the accumulation of acids or loss of bicarbonate, while metabolic alkalosis happens when there is excessive bicarbonate retention or acid loss.
Thus, if you are hyperventilating due to stress or anxiety, your body is more likely to experience respiratory alkalosis due to the excessive loss of CO₂.