Cerebrospinal fluid functions like “protective pillow” for nervous tissue. Cerebrospinal fluid (CSF) is produced in the ventricle plexus choroideus (choroid plexus) by the plasma ultrafiltration, active plexus cell activity, differential absorption, active secretion, and intensive metabolic change through cerebral ventricles ependyma and basal glial membrane. Metabolic change is carried out also among pial vessels and liquor spaces. CSF fills the subarachnoid space within/around the CNS and is absorbed by the dural arachnoid villi sinuses. The subarachnoid space, which lies between the arachnoid membrane externally and the pia mater internally, carries the flow from the cerebral ventricles to its points of absorption. The subarachnoid space extends superficially over the whole surface of the brain and spinal cord. Every blood vessel entering or leaving the nervous system must pass across it. Total CSF volume is about 70–150 ml (10–60 ml in newborn), 500–600 ml is formed daily, and the entire volume is renewed every 5–7 hours. There is also known to be a constant process of dialysis with exchange of various chemical constituents between the CSF and the blood across the ventricular ependyma, the perivascular spaces and the arachnoid membrane at all levels. Some CSF constituants concentrations are regulated within narrow limits: K+, H+, Mg2+, Ca2+. Glucose, urea and creatinine diffuse freely but require several hours for equilibration. CSF analytes concentrations should always be compared with those in plasma, because alterations in the latter are reflected in the CSF even when CNS metabolism is normal.
KeywordsMultiple Sclerosis Herpes Zoster Bacterial Meningitis Cerebral Malaria Test Purpose
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