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

This occurs when cancer cells migrate through the blood-brain barrier. —Kayla Grant, People.com, 18 Apr. 2025

The curcumin in turmeric can cross the blood-brain barrier (the semi-permeable membrane that separates the blood from the brain tissue) and may decrease protein buildup associated with neurodegenerative diseases. —Lindsay Curtis, Verywell Health, 2 Apr. 2025

The brain is surrounded by a difficult-to-penetrate barrier called the blood-brain barrier, which blocks toxins from entering. —Kaitlin Sullivan, NBC News, 19 Mar. 2025

That artificial sweetener crosses your blood-brain barrier and actually makes the neurotransmitter depletion worse. —Andrea Margolis, FOXNews.com, 7 July 2025

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