What is the approximate partial pressure of oxygen (PO2) at sea level?

What is the approximate partial pressure of oxygen (PO2) at sea level?

• A. 100 mmHg
• B. 159 mmHg
• C. 760 mmHg
• D. 47 mmHg

Answer: (B)

The partial pressure of oxygen (PO2) at sea level is approximately 159 mmHg. This value is derived from the composition of atmospheric air, which is roughly 21% oxygen. At sea level, the total atmospheric pressure is about 760 mmHg. To calculate the partial pressure of oxygen, you multiply the total pressure by the fraction of air that is oxygen: PO2 = Total Atmospheric Pressure × Fraction of Oxygen PO2 = 760 mmHg × 0.21 ≈ 159 mmHg This calculation highlights how the atmosphere's pressure and gas composition determine the availability of oxygen. Understanding this value is crucial in various clinical contexts, such as interpreting arterial blood gases and assessing respiratory function. The other choices reflect pressures that do not align with the accurate representation of PO2 at sea level, reinforcing the importance of recognizing the standard atmospheric conditions for physiological studies.

The partial pressure of oxygen (PO2) at sea level is approximately 159 mmHg. This value is derived from the composition of atmospheric air, which is roughly 21% oxygen. At sea level, the total atmospheric pressure is about 760 mmHg. To calculate the partial pressure of oxygen, you multiply the total pressure by the fraction of air that is oxygen:

PO2 = Total Atmospheric Pressure × Fraction of Oxygen

PO2 = 760 mmHg × 0.21 ≈ 159 mmHg

This calculation highlights how the atmosphere's pressure and gas composition determine the availability of oxygen. Understanding this value is crucial in various clinical contexts, such as interpreting arterial blood gases and assessing respiratory function. The other choices reflect pressures that do not align with the accurate representation of PO2 at sea level, reinforcing the importance of recognizing the standard atmospheric conditions for physiological studies.