Blood–brain barrier

The Blood–brain barrier (BBB) is a highly selective permeability barrier that separates the circulating blood from the brain and extracellular fluid in the central nervous system (CNS). It is formed by brain endothelial cells connected by tight junctions, which restrict the passage of substances from the bloodstream, thereby protecting the brain from potentially harmful chemicals while allowing essential nutrients to pass through. The BBB is crucial for maintaining the brain's microenvironment and poses challenges for delivering therapeutic agents to treat neurological disorders.