Under Quiet Conditions, Blood Returning to the Heart Retains About

Question

Under quiet conditions, blood returning to the heart retains about ________ of its oxygen content.
A) 25 percent
B) 50 percent
C) 75 percent
D) 90 percent
E) 100 percent

Accepted Answer

Under quiet conditions, blood returning to the heart retains about 75 percent of its oxygen content. This is because the body's tissues only use about 25% of the oxygen carried by the blood under these conditions, leaving the majority of the oxygen still in the blood as it returns to the heart.