What is the function of the blood-brain barrier? preventing blood loss during injury regulating blood flow through the brain keeping brain blood separate from body blood keeping foreign particles out of the brain?

The correct answer is that it helps to keep the foreign substances out of the brain.

Explanation:

A highly selective semipermeable outline, which distinguishes the circulating blood from the brain and the extracellular fluid in the CNS is termed as the blood-brain barrier. This system permits the entry of certain molecules by passive diffusion and at the same time selective mediation of molecules like water, glucose, and amino acids, which plays an essential role in the function of brain.  

The blood-brain barrier performs various essential activities. Some of the functions of the barrier are to safeguard the brain from the foreign particles present in the blood, which could harm the brain, and to maintain a constant environment for the proper functioning of the brain.  

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