CLINICAL MEDICINE

Detailed explanation-1: -The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside.

Detailed explanation-2: -The blood-brain barrier (BBB), first described by Paul Ehlrich (1885), is a highly selective semi-permeable membrane between the blood and brain interstitium. This unique barrier allows cerebral blood vessels to regulate the movement of molecules and ions between the blood and the brain.

Detailed explanation-3: -The blood-brain barrier is the barrier between the cerebral capillary blood and the interstitial fluid of the brain. It is made up of capillary endothelial cells and basement membrane, neuroglial membrane, and glial podocytes, i.e., projections of astrocytes.

Detailed explanation-4: -Instead, the blood-CSF barrier at the choroid plexus is formed by the epithelial cells and the tight junctions that link them. The other part of the blood-CSF barrier is the arachnoid membrane, which envelops the brain. The cells of this membrane also are linked by tight junctions.

Detailed explanation-5: -(1) Small ions and water molecules can cross the blood-brain barrier through ion channels. (2) Small lipophilic molecules that are soluble in the hydrophobic core of the cell membrane can be transported passively across the cell.