Wiktionary
n. (context anatomy English) A structure in the central nervous system (CNS) that keeps various substances found in the bloodstream out of the brain while allowing in the substances essential to metabolic function, e.g. oxygen.
WordNet
n. a mechanism that creates a barrier between brain tissues and circulating blood; serves to protect the central nervous system; "the brain was protected from the large molecules of the virus by the blood-brain barrier"
Usage examples of "blood-brain barrier".
The existence of a tumor can destroy the blood-brain barrier in the region of the tumor.
But glucose is one molecule that gets through the blood-brain barrier easily.
What if they crossed the blood-brain barrier and found out about me -- the brain's real function.
He had to force himself to slow down and concentrate, and when he did he learned that deoxy-glucose was so similar to glucose, the biological fuel of the brain, that it was transported across the blood-brain barrier and picked up by the active nerve cells.
Or, if that didn't happen, maybe you're still right, and antibiotics that cross the blood-brain barrier—.
The tricky part was to keep the molecule lipid soluble, so it would cross the blood-brain barrier.
But if one were to electrically stimulate the perforant pathway to the hippocampus, and get a great deal of adenosine tri-phosphate past the blood-brain barrier, for instance, thus stimulating the long-term potentiation that aided learning in the first place.