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

Cancer cells can enter the brain by crossing the blood-brain barrier, a protective mechanism designed to keep harmful substances out of the brain. —Julie Scott, Msn, Anp-Bc, People.com, 28 Feb. 2025

In addition to a thick skull, the blood-brain barrier (BBB), a natural protective membrane, prevents microscopic intruders such as toxins and pathogens from entering the nervous system. —Jenny Lehmann, Discover Magazine, 26 Feb. 2025

Biochemical fallout The primary stage of traumatic brain injury can severely damage and even destroy the blood-brain barrier – an interface protecting the brain by limiting what can enter it. —Aaron Priester, The Conversation, 19 Feb. 2025

Finding the particles in higher concentrations in the brain was a surprise because of the blood-brain barrier, which protects the brain against infection. —Elizabeth Weise, USA TODAY, 3 Feb. 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