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While a runner rests before a race, the hemoglobin in the blood returning to her

ID: 255170 • Letter: W

Question

While a runner rests before a race, the hemoglobin in the blood returning to her heart is 75% saturated with oxygen. While she is running, this percentage

While a runner rests before a race, the hemoglobin in the blood returning to her heart is 75% saturated with oxygen. While she is running, this percentage

decreases because the partial pressure of oxygen in her alveoli is reduced below 40 mm Hg. stays the same because hemoglobin is usually 75% saturated with oxygen. increases because she is breathing harder. decreases because the decreased PO2 in her muscles makes it easier for additional oxygen to be released from the hemoglobin. increases because her muscles need more oxygen.

Explanation / Answer

Ans : decreases because the partial pressure of oxygen in her alveoli is reduced below 40 mm Hg

The hemoglobin carries oxygen from the lungs to the muscles , where it can be utilised by the cells to burn fuel and produce energy.

So when the runner runs the race , it requires energy , so the pO2 in alveoli decreases , as it is utilised by the body.