Brain metabolism and the autoregulation of cerebral blood flow
The brain's oxygen and glucose demand, its fuels (glucose, lactate and ketones), the ischaemic thresholds behind the penumbra, and how pressure autoregulation, carbon dioxide, oxygen and neurovascular coupling set cerebral blood flow, applied to stroke, hypertensive emergency, hyperventilation, hypoglycaemia and Wernicke encephalopathy.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The brain is about 2% of body weight but takes 15% of cardiac output, 20% of resting oxygen and about 25% of glucose (around 120 g a day).
- It stores almost no energy. Consciousness is lost about 10 seconds after circulation stops and irreversible injury begins after about 4 to 5 minutes.
- Normal cerebral blood flow (CBF) is about 50 mL/100 g/min (grey matter about 80, white matter about 20).
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Sources
- Principles of Neural Science (6th ed.)McGraw Hill (Kandel, Koester, Mack and Siegelbaum, 2021), 2021
- Guyton and Hall Textbook of Medical Physiology (14th ed.)Elsevier (Hall and Hall, 2021), 2021
- Carney N et al. Guidelines for the Management of Severe Traumatic Brain Injury, Fourth Edition. Neurosurgery 2017;80:6-15Brain Trauma Foundation, 2017
- Last updated
- 14 November 2026
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