What is the normal PCO2 level in arterial blood?

The normal PCO2 level in arterial blood is typically around 40 mmHg. This level is significant because it reflects the balance between the production of carbon dioxide (CO2) in the body and the elimination of CO2 through the lungs during the process of respiration.

A PCO2 level of 40 mmHg is considered the standard reference value in healthy adults under normal physiological conditions. It indicates effective ventilation, where the system is adequately removing CO2 generated from metabolic processes. Deviations from this normal range can indicate respiratory or metabolic disturbances. For instance, lower levels, such as 35 mmHg, may suggest hyperventilation or respiratory alkalosis, while higher levels, like 45 mmHg or above, could indicate hypoventilation or respiratory acidosis.

In summary, the correct answer reflects the normal physiological range for PCO2, highlighting its critical role in assessing respiratory function and maintaining acid-base balance in the body.