Which statement best describes PaO2?

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Multiple Choice

Which statement best describes PaO2?

PaO2 represents the arterial oxygen tension—the pressure of dissolved oxygen in arterial blood. This arterial O2 tension sets the driving force for oxygen diffusion from the blood to tissues and thus reflects how well oxygen is delivered systemically. Describing PaO2 as the gradient between tissues and arterial oxygen captures that diffusion-driving idea, since the movement of oxygen depends on the difference in oxygen partial pressures across the capillary wall and into tissues. It's important to separate this from other related measures: oxygen saturation (SaO2) tells you how much hemoglobin is bound with oxygen, not the dissolved oxygen pressure. The partial pressure of carbon dioxide is PaCO2, a different gas. Oxygen content (CaO2) combines the dissolved O2 (PaO2) with the oxygen bound to hemoglobin, so PaO2 alone does not equal the total oxygen carried.

PaO2 represents the arterial oxygen tension—the pressure of dissolved oxygen in arterial blood. This arterial O2 tension sets the driving force for oxygen diffusion from the blood to tissues and thus reflects how well oxygen is delivered systemically. Describing PaO2 as the gradient between tissues and arterial oxygen captures that diffusion-driving idea, since the movement of oxygen depends on the difference in oxygen partial pressures across the capillary wall and into tissues.

It's important to separate this from other related measures: oxygen saturation (SaO2) tells you how much hemoglobin is bound with oxygen, not the dissolved oxygen pressure. The partial pressure of carbon dioxide is PaCO2, a different gas. Oxygen content (CaO2) combines the dissolved O2 (PaO2) with the oxygen bound to hemoglobin, so PaO2 alone does not equal the total oxygen carried.

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