blood-brain barrier

[bluhd-breyn]

noun

Physiology.

1. a layer of tightly packed cells that make up the walls of brain capillaries and prevent substances in the blood from diffusing freely into the brain: passage across the cell membranes is determined by solubility in the lipid bilayer or recognition by a transport molecule.

blood-brain barrier

1. A physiological mechanism that alters the permeability of capillaries in the brain, so that some substances, such as certain drugs, are prevented from entering brain tissue, while other substances are allowed to enter freely.

blood-brain barrier

1. The separation of the brain, which is bathed in a clear cerebrospinal fluid, from the bloodstream. The cells near the capillary beds external to the brain selectively filter the molecules that are allowed to enter the brain, creating a more stable, nearly pathogen-free environment.

Oxygen, glucose, and white blood cells are molecules that are able to pass through this barrier. Red blood cells cannot.

Word History and Origins

Origin of blood-brain barrier¹

First recorded in 1940–45

Example Sentences

The team also observed the early weakening of the blood-brain barrier, which normally regulates nutrient flow into the brain and prevents harmful substances from entering.

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The drug is unable to cross the blood-brain barrier and so does not help with cognitive symptoms.

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Using this understanding, the research team created molecules that can cross the blood-brain barrier and remove copper from beta-amyloid plaques.

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The main obstacle for researchers was the blood-brain barrier, a protective system that shields the brain from harmful substances.

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Their smaller size allows them to cross the blood-brain barrier and act on targets more efficiently, which could lead to improved outcomes with fewer adverse reactions.

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