Question

Choose the correct answer from the alternatives given.
Compared to the interstitial fluid that bathes active muscle cells, blood reaching that tissue in arteries has a

• A. higher $P{O}_2$
• B. higher $PC{O}_2$
• C. greater hydrogencarbonate concentration
• D. lower pH

Answer 1

The correct option is A higher $P{O}_2$

A difference in partial pressure helps in exchange of gases. Therefore, a difference in partial pressure of oxygen also exists between the arteries (carrying oxygenated blood) and the metabolically active tissues, with the partial pressure in the metabolically active tissues being lower than that in the arteries. The partial pressure of oxygen in tissues is about 40 mm Hg because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood in arteries is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue. So, the correct option is ' higher pO${}_2$'.