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Central Nervous System

1 out of 10

CSF pressure depends primarily upon? (AIIMS NOV 2008)

A Rate of formation from choroid plexus

B Rate of absorption

C Cerebral blood flow

D Blood pressure

Ans. B Rate of absorption

Normal CSF pressure is mainly regulated by rate of absorption by arachnoid villi.

  1. The normal rate of CSF formation remains nearly very constant. It is independent of the CSF pressure.
  2. Absorption by arachnoid villi is proportionate to the CSF pressure

(Arachnoid villi act like valves and allow CSF fluid to flow into venous sinuses when CSF pressure is about 1.5mm Hg greater than the pressure of blood in the venous sinuses. If the CSF pressure rises further, the valves open more widely, so that under normal conditions, the CSF pressure almost never rises more than a few mm of Hg higher than the pressure in the cerebral venous sinuses)

CSF formation and absorption in humans at various CSF pressure.