Where is Blood-Brain Barrier Located?
BBB is located at the brain blood capillaries. These capillaries are unusual in several aspects from capillaries in other organs. Those aspects are briefly described below: The end-points of cells which make up the walls of these capillaries are sealed together at their edges by tight junctions which are a key component in the barrier. These junctions make sure that water soluble substances in the blood don’t pass between the edges of cells. These capillaries are enclosed by flattened cells which altogether called the ‘end-feet’ which also work as a (partial and active) barrier. The only way for water soluble substances in the blood is through the walls of capillaries. These walls plays the other role in the barrier because their cell membranes are made up of a lipid/protein belayed only allowing flat-soluble molecules including those of oxygen and carbon dioxide, anesthetics and alcohol to pass through the walls of capillaries. In the capillary wall there are three classes of ‘efflux
