The prevents access of microbes in the blood from gaining access to the central nervous system.

The blood-brain barrier prevents access of microbes in the blood from gaining access to the central nervous system.

Explanation:

The Blood - Brain barrier -

The tissues present in the central nervous system have some extra protection , such that the unexposed blood or the immune system in the similar way as the other tissues . The blood vessels which supply the brain with the nutrients lies on the top of pia mater .

Now , due to this , the materials in the circulatory system have very limited ability to interact with central nervous system . This very process is called the blood - brain barrier .

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