Blood-Brain Barrier

 

Blood vessels are critical to delivering oxygen and nutrients to all or any of the tissues and organs throughout the body. The blood vessels that vascularize the central systema nervosum (CNS) possess unique properties, termed the barrier, which allows these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and therefore the brain. 

Extra Info:

The BBB's unique structure and the tightly regulated interplay of its cellular and acellular components allow for maintenance of brain homeostasis- which life itself depends on this-.