blood-brain barrier

American  

[bluhd-breyn] / ˈblʌdˈbreɪn /

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.

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blood-brain barrier Scientific  

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.

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blood-brain barrier Cultural  

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.

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Discover More

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

Etymology

Origin of blood-brain barrier

First recorded in 1940–45

Example Sentences

As people grow older, the blood-brain barrier becomes more fragile.

From Science Daily

Some scientists were sceptical because this would require the particles to cross the powerful defences of the blood-brain barrier.

From Barron's

This included breakdown of the blood-brain barrier, damage to nerve fibers, chronic inflammation, reduced formation of new neurons in the hippocampus, weakened communication between brain cells, and extensive oxidative damage.

From Science Daily

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.

From Science Daily

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

From BBC