That depends on whether you are asking about the red blood cells themselves, or the blood as a whole. The fluid portion of the blood will have a O2 partial pressure around 20%, but the red blood cells will have an O2 partial pressure nearing 100%.
The partial pressure of oxygen in expired air is 109 mmHg. Partial pressure is calculated at the proportion of oxygen in the air, so at 1 atmosphere for dry air pressure is 713 mmHg (which is 760 total pressure - 47 mmHg water vapor) and oxygen is 21% of the dry gas concentration so inspired pO2 is 150 mmHg.
Yes, the partial pressure of oxygen in the arteries is typically greater than in the veins. This is because oxygen is being delivered to tissues by the arterial blood, so the arterial blood has higher oxygen levels compared to the venous blood, which has already passed through the tissues and picked up carbon dioxide.
PCO2 refers to the partial pressure of carbon dioxide in the blood, while PaCO2 specifically refers to the partial pressure of carbon dioxide in arterial blood. Arterial blood is the blood that has been oxygenated in the lungs and is then circulated to the rest of the body. The PaCO2 measurement is more precise and important in clinical assessments compared to just PCO2.
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Because of difference in partial pressure
The partial pressure of carbon dioxide in venous blood is around 40 mmHg.
Oxygen and carbon dioxide levels in the blood are evaluated using a blood gas test, which analyzes the partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2) in arterial blood. pH levels are also measured as part of this test to assess the acidity or alkalinity of the blood.
C02:alveoli
Alveolar carbon dioxide partial pressure can be calculated using the alveolar gas equation: PaCO2 = (Pb-PH2O) * FiCO2 - (PaCO2 / R), where PaCO2 is the alveolar partial pressure of carbon dioxide, Pb is barometric pressure, PH2O is water vapor pressure, FiCO2 is inspired fraction of CO2, and R is the respiratory quotient. This equation helps estimate the partial pressure of CO2 in the alveoli.
To find the partial pressure of oxygen, you can subtract the partial pressures of helium and carbon dioxide from the total pressure of 1 atmosphere (760 mm Hg). Partial pressure of oxygen = Total pressure - Partial pressure of helium - Partial pressure of carbon dioxide = 760 mm Hg - 609.5 mm Hg - 0.5 mm Hg = 150 mm Hg.
metabolic acidosis
The concentration of Carbon Dioxide in arterial blood. Partial (Pa) Carbon Dioxide (CO2) pressure in ABG.