blood-brain barrier

noun

ˈbləd-ˈbrān- 

: a naturally occurring barrier created by the modification of brain capillaries (as by reduction in fenestration and formation of tight cell-to-cell contacts) that prevents many substances from leaving the blood and crossing the capillary walls into the brain tissues

Examples of blood-brain barrier in a Sentence

Recent Examples on the Web

As the infection advances, the fly’s blood-brain barrier becomes permeable, allowing the fungus to manipulate neural circuits with even greater precision. —Scott Travers, Forbes, 24 Nov. 2024

Neurotransmitters become unbalanced, and the blood-brain barrier becomes more permeable. —Janelle McSwiggin, Msn, Health, 25 Sep. 2024

That’s because the brain is surrounded by a semipermeable membrane called the blood-brain barrier. —Kaitlin Sullivan, NBC News, 16 Sep. 2024

Nelson pointed to evidence of changes to bone health, to the blood-brain barrier of the central nervous system, and to particular features in the eye as areas of open research. —Georgina Torbet, The Verge, 16 Aug. 2024

Word History

First Known Use

1934, in the meaning defined above

Medical Definition

blood-brain barrier

noun

: a naturally occurring barrier created by the modification of brain capillaries (as by reduction in fenestration and formation of tight cell-to-cell contacts) that prevents many substances from leaving the blood and crossing the capillary walls into the brain tissues

—abbreviation BBB