3.11.2. QN: CSF
ICP range = 5-15mmHg
Facts about CSF
- Volume of CSF = 150mL
- pH = 7.33
- pCO2 = 50mmHg
- Low proteiin (20mg/L)
- Low glucose
- [Cl] higher, [K] lower than plasma
- Very low cholesterol content
Production of CSF
- 500-600mL/day
- Production affected by cerebral blood flow, NOT by ICP
- >67% from choroid plexus
- <33% directly from ependyma of the walls of ventricles
Absorption of CSF
- Increases linearly with ICP when CSF pressure raises above 6.8cmH2O
- Below that, constant absorption
- 90% by arachnoid villi
- 10% directly into cerebral venules