19) THE CEREBRO SPINAL FLUID

[Editor]

a) contains virtually no glucose
b) the pH does not accurately reflect plasma pH
c) is secreted by the choriod plexus
d) is reabsorbed by the arachnoid villi
e) pressure increases with compression of the jugular veins

[Editor]

FTTTT

The cerebrospinal fluid is an ultraflitrate of plasma with a few alterations to its ionic composition. The sugar content is approximately 50% that of the plasma. It also contains a lower concentration of plasma proteins hence a reduced buffering capacity.
It is produced at a rate of 0.5mls/min (approx 450 mls) per day in the adult. One third of it is located in the brain with the remaining 2/3rdslocated around the spinal cord. it is secreted by the choroids plexus and reabsorbed by the arachnoid villi. Pressure changes within the skull obey the Munroe Kellie doctrine.

[Tonic]

I believe CSF pH does accurately reflect blood pH. Yes the pH is lower and there is less buffering capacity, but decrease in CSF pH due to hypercarbia stimulates central chemoreceptors, thus reflecting blood pH!