- About 2% of total body mass (1.4 kg)
Volume of intracranial contents
- 1700 ml
- Can be divided into three physiologic compartments
- Adults
- Brain parenchyma ≈ 1400 ml (80%)
- 10% is solid material
- 70% is tissue water
- Cerebral blood volume (CBV) ≈ 150 ml (10%)
- CSF ≈ 150 ml (10%)
- 75ml 50% in cranium
- Ventricular CSF 25 ml
- 75ml 50% in spine
- CSF production
- 600mls/day
- 30mls/hr
- 0.5ml/min
- Infant
- CSF production
- 400ml/day
- Neonates
- CSF = 50 ml
- Ventricular CSF 25 ml
- CSF production
- 25ml/day
- 1ml/hr
- 0.01ml/min
The high metabolic activity of the brain
- 20% of basal oxygen consumption
- 25% of basal glucose consumption
- Resting energy expenditure by organ
- Brain 22%,
- Liver 21%,
- Heart 9%
- Kidneys 8%
- Cellular function
- Maintenance of transmembrane electrical and ionic gradients (≈ 60%)
- Maintenance of membrane structure and integrity and the synthesis and release of neurotransmitters (≈ 40%)
- 20% of cardiac output (750 ml/min in adults) at rest,
- Equates to an average CBF of about 50 ml/100 g/min.
Made with Bullet