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

Examples of blood-brain barrier in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The novel drug-delivery method that breaches the blood-brain barrier could be usedto treat a host of diseases that afflict millions — like Alzheimer's, Parkinson's and a deadly condition associated with cancer. Kale Williams, Axios, 21 Apr. 2025 Once ingested by a human, methylmercury isn’t easily excreted and can quickly cross the digestive tract, the blood-brain barrier, and the placenta. Mack Degeurin, Popular Science, 12 Feb. 2025 Salinas hypothesized that these species may have colonized the fish brains early in their development, before their blood-brain barriers had fully formed. Yasemin Saplakoglu, WIRED, 5 Jan. 2025 Stress increases inflammation in the brain, making the blood-brain barrier weaker and more permeable. William A. Haseltine, Forbes, 25 Mar. 2025 See All Example Sentences for blood-brain barrier

Word History

First Known Use

1934, in the meaning defined above

Time Traveler
The first known use of blood-brain barrier was in 1934

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Cite this Entry

“Blood-brain barrier.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/blood-brain%20barrier. Accessed 6 May. 2025.

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

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