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

Determining whether changes in the blood-brain barrier, inflammation, genetics, lifestyle or other factors initiate this process will be an important next step. — Melissa Rudy, FOXNews.com, 25 Aug. 2026

But brain cancers are especially challenging to treat because many emerging therapies such as antibody-drug conjugates can’t pass through the blood-brain barrier. — Isabella Backman, Hartford Courant, 24 Aug. 2026

The nicotine salt allows the nicotine to cross the blood-brain barrier more easily, making higher levels of nicotine more palatable, according to King. — Callie Teitelbaum, CBS News, 5 Aug. 2026

These proteins are usually flushed into the bloodstream through the blood-brain barrier. — Devika Rao, TheWeek, 26 June 2026

Word History

First Known Use

1934, in the meaning defined above

Rhymes for blood-brain barrier

• noncarrier
• carrier

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