Type O negative blood (red cells) can be transfused to patients of all blood types. It is always in great demand and often in short supply. Type AB positive plasma can be transfused to patients of all other blood types. AB plasma is also usually in short supply.
Blood-brain barrier. A blockade of cells separating the circulating blood from elements of the central nervous system (CNS); it acts as a filter, preventing many substances from entering the central nervous system.
The BBB is distinct from the quite similar bloodâcerebrospinal-fluid barrier, which is a function of the choroidal cells of the choroid plexus, and from the bloodâretinal barrier, which can be considered a part of the whole realm of such barriers. Several areas of the human brain are not on the brain side of the BBB. small number of regions in the brain, including the circumventricular organs (CVOs), do not have a bloodâbrain barrier. The bloodâbrain barrier occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation.