Question

Normal cerebral blood flow is approximately how many ml/min?

• A. 55
• B. 150
• C. 750
• D. 1000

Hint:

The brain gets about 15 percent of cardiac output; the 55 figure is per 100 g, not total.

Answer 1

The Correct Option is C

Step 1: Total cerebral blood flow in an adult is about 750 ml/min, which is roughly 15 percent of the resting cardiac output. This high share reflects the brain's large and constant metabolic demand.

Step 2: Expressed per unit tissue, this works out to about 50 to 55 ml per 100 g of brain tissue per minute. The figure of 55 in the options refers to this per-100-g value, not the whole-brain flow, so it does not answer the question as asked (ml/min for the whole brain).

Step 3: Cerebral blood flow is tightly autoregulated and stays nearly constant over a wide range of mean arterial pressures. The correct whole-brain value in ml/min is therefore 750.