A medical illustration showing the cross sectional view of a normal vessel and a brain blood vessel. The normal blood vessel shows water-lined pores, pore passages, and the ability of lipid-soluble substances to travel out of the vessel. The brain blood vessel shows glial brain cells to support the blood brain barrier, tight junctions that create the barrier (no pores), and the ability of carrier-mediated transport and lipid-soluble substances to travel across the blood brain barrier from the vessel.
