Definition

Noun: A highly selective semipermeable border of endothelial cells that prevents most solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside. Its primary function is to protect the brain from potentially harmful substances while allowing essential nutrients to pass through.

Usage

The term is used in medical, biological, and pharmacological contexts to describe this specific physiological structure and its function. - The effectiveness of many drugs is limited because they cannot cross the blood-brain barrier. - Researchers are studying ways to temporarily open the blood-brain barrier to deliver chemotherapy to brain tumors.

Advanced Usage

• "To cross/penetrate the blood-brain barrier": Describes the ability of a substance to pass through this barrier.
  • Only small, lipid-soluble molecules can easily cross the blood-brain barrier.
• "Blood-brain barrier integrity": Refers to the proper, undamaged state of the barrier.
  • The infection threatened the blood-brain barrier integrity, leading to inflammation.

Variants and Related Words

• BBB: A common initialism for "blood-brain barrier."
• Blood-CSF barrier (Blood-Cerebrospinal Fluid barrier): A related but distinct barrier system.
• Neurovascular unit: A modern conceptual framework that includes the blood-brain barrier along with surrounding cells like astrocytes and pericytes.

Synonyms

• Hematoencephalic barrier (less common variant).
• Brain barrier.

Related Phrases

• Blood-brain barrier disruption: A breakdown or compromise of the barrier's function.
• Blood-brain barrier permeability: The degree to which the barrier allows substances to pass.

Noun

1. a mechanism that creates a barrier between brain tissues and circulating blood; serves to protect the central nervous system
   • the brain was protected from the large molecules of the virus by the blood-brain barrier