What is the normal cerebral metabolic rate for oxygen (CMRO2) in mL of oxygen per 100 g of brain tissue per minute?

What is the normal cerebral metabolic rate for oxygen (CMRO2) in mL of oxygen per 100 g of brain tissue per minute?

• A. 0.5 mL/100 g/min
• B. 2.0 mL/100 g/min
• C. 3.5 mL/100 g/min
• D. 7.5 mL/100 g/min

Answer: (C)

Normal CMRO2 is the brain’s oxygen consumption per minute per 100 g of brain tissue. At rest, this value is about 3.5 mL of O2 per 100 g of brain tissue each minute. This reflects the balance between oxygen delivery by cerebral blood flow and the amount of oxygen the tissue extracts from the blood. The brain makes only small adjustments to meet metabolic demand, keeping CMRO2 relatively stable under normal conditions. That’s why 3.5 mL/100 g/min is the standard resting value you’re expected to recall. Values much lower or higher would indicate a state far from baseline metabolism, so the other options don’t fit the typical resting rate.

Normal CMRO2 is the brain’s oxygen consumption per minute per 100 g of brain tissue. At rest, this value is about 3.5 mL of O2 per 100 g of brain tissue each minute. This reflects the balance between oxygen delivery by cerebral blood flow and the amount of oxygen the tissue extracts from the blood. The brain makes only small adjustments to meet metabolic demand, keeping CMRO2 relatively stable under normal conditions. That’s why 3.5 mL/100 g/min is the standard resting value you’re expected to recall. Values much lower or higher would indicate a state far from baseline metabolism, so the other options don’t fit the typical resting rate.