Body & HealthFact

Your brain has its own border control with bouncers.

The blood–brain barrier arises because the cells lining brain capillaries are sealed by tight junctions, wrapped by astrocyte end-feet and pericytes. Oxygen and CO2 diffuse through; glucose and amino acids need transporters. More than 98 percent of all small-molecule drugs never get in at all.

Useful: Explains why many substances that work in a dish never reach the brain.

Source: en.wikipedia.org

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