<P> The blood -- brain barrier ( BBB ) is a highly selective semipermeable membrane barrier that separates the circulating blood from the brain and extracellular fluid in the central nervous system ( CNS ) . The blood -- brain barrier is formed by brain endothelial cells and it allows the passage of water , some gases , and lipid - soluble molecules by passive diffusion , as well as the selective transport of molecules such as glucose and amino acids that are crucial to neural function . Furthermore , it prevents the entry of lipophilic potential neurotoxins by way of an active transport mechanism mediated by P - glycoprotein . Astrocytes have been claimed to be necessary to create the blood -- brain barrier . A few regions in the brain , including the circumventricular organs , do not have a blood -- brain barrier . </P>
<P> The blood -- brain barrier ( BBB ) is a highly selective semipermeable membrane barrier that separates the circulating blood from the brain and extracellular fluid in the central nervous system ( CNS ) . The blood -- brain barrier is formed by brain endothelial cells and it allows the passage of water , some gases , and lipid - soluble molecules by passive diffusion , as well as the selective transport of molecules such as glucose and amino acids that are crucial to neural function . Furthermore , it prevents the entry of lipophilic potential neurotoxins by way of an active transport mechanism mediated by P - glycoprotein . Astrocytes have been claimed to be necessary to create the blood -- brain barrier . A few regions in the brain , including the circumventricular organs , do not have a blood -- brain barrier . </P>
which type of cell forms the blood brain barrier
which type of cell forms the blood brain barrier
endothelial cells
endothelial cells