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