Intoduction

Cerebrospinal fluid (CSF) is a clear fluid that occupies the ventricular system and subarachnoid space around and inside the brain. It is approximately isotonic and cushions the brain.

Cerebrospinal fluid can be responsible for intracranial pressure.

Unlike other organs brain tissues have tight junctions that almost fuse adjacent cells. This creates a blood brain barrier. Small molecules such as oxygen and carbon dioxide cross this barrier easily but larger molecules such as amino acids and glucose can only cross the blood brain barrier with the help of transporter proteins. The blood brain barrier protects the brain from toxic substances but impedes also the entry of drugs.

The CSF provides brain tissue with essential nutrients and moves toxic subtances away from the brain.

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