Which statement about respiratory alkalosis is true?

Which statement about respiratory alkalosis is true?

• A. It Is Caused by Decreased Ventilation
• B. It Is Typically Caused by Increased PCO2
• C. It Is Characterized by Increased pH and Decreased PCO2
• D. It Is Associated with Metabolic Acidosis

Answer: (C)

When the body is in respiratory alkalosis, the main change is excessive breathing that blows off CO2 faster than it's produced. CO2 in the blood forms carbonic acid, which lowers pH. As CO2 falls, there are fewer hydrogen ions, so the pH rises. That combination—high pH with low PCO2—is the hallmark of this condition. Think of it this way: increased ventilation reduces arterial CO2, shifting the chemical balance toward alkalinity. The kidneys may compensate over time by excreting more bicarbonate to help bring pH back toward normal. The other statements don’t fit because decreased ventilation causes CO2 to accumulate and pH to fall (respiratory acidosis), increased CO2 would also lower pH, and metabolic acidosis involves a primary drop in bicarbonate with low pH, not a primary low CO2 with high pH.

When the body is in respiratory alkalosis, the main change is excessive breathing that blows off CO2 faster than it's produced. CO2 in the blood forms carbonic acid, which lowers pH. As CO2 falls, there are fewer hydrogen ions, so the pH rises. That combination—high pH with low PCO2—is the hallmark of this condition.

Think of it this way: increased ventilation reduces arterial CO2, shifting the chemical balance toward alkalinity. The kidneys may compensate over time by excreting more bicarbonate to help bring pH back toward normal.

The other statements don’t fit because decreased ventilation causes CO2 to accumulate and pH to fall (respiratory acidosis), increased CO2 would also lower pH, and metabolic acidosis involves a primary drop in bicarbonate with low pH, not a primary low CO2 with high pH.