When You Are Lying on the Couch, Resting, the Blood

Multiple Choice

When you are lying on the couch, resting, the blood going from your heart to your lungs is approximately _______ % saturated with oxygen.When you are running fast on a treadmill, _______.

A) 0; your active muscles extract most of the oxygen bound to hemoglobin
B) 25; your active muscles extract all the oxygen that is bound to hemoglobin
C) 50; the partial pressure of oxygen in your active muscles is high, causing most bound oxygen to be released from hemoglobin in these tissues
D) 75; the lower partial pressure of oxygen in your active muscles causes hemoglobin to release more bound oxygen to these tissues
E) 100; the partial pressure of oxygen in your blood falls below 40 mm Hg