Abstract
The blood-brain barrier (BBB) is the highly specialized and selective crossing area between blood and brain, essential for brain homeostasis and functioning, formed by the endothelial cells of the cerebral microvasculature in a rich and intimate cooperation with the neighboring cells and local signaling factors from both the brain and blood sides. Its distribution throughout the brain is following the brain cytoarchitectonic patterns, each capillary serving the adjacent neurons in a privileged neurovascular interplay that ultimately responds to the manifestation of brain functions, scaled from the cellular to the system level. At the edge of our understanding, cognition stands for what makes us humans and needs the cooperation of the entire body functioning to assist homeostatic favorable conditions for its manifestation. The cerebral endothelial system is operating at this interfacing point, modulating its own phenotype in accordance with various conditions to which the organism and brain are exposed, responding with changes in its permeability and signaling processes. In this chapter we will briefly describe the multicellular assembly of the neurovascular unit from which the BBB emerges, and its contribution to the brain homeostasis by dynamic neurovascular and neurometabolic coupling processes. Further, we will refer to the principal morphologic and functional features of the BBB from which its specific properties arise, making it not just a physical selective barrier, but also a metabolic, neuroimmune and endocrine interface. We will touch on the physiological implications of BBB and neurovascular coupling on high brain functions and cognition, in normal or disease-associated conditions.
