What Exactly Is the Blood Brain Barrier?

Our brains are choosy about what they let in, and that’s thanks to the blood brain barrier. In this episode, Patrick explores how this anatomical separation between our blood and brain keeps us safe from potential harm. » Subscribe to Seeker! » Watch more Human! » Visit our shop at The heart pumps oxygenated blood through arteries into systemic circulation, then those arteries branch out into tinier and tinier blood vessels called capillaries that surround different tissues. Capillaries have really thin walls, and oxygen, carbon dioxide, and other compounds can diffuse through those walls to get in or out of the blood stream. And just like any other organ, the central nervous system, which includes the brain and spinal cord, gets oxygen and nutrients from the blood. But these organs are a little more sensitive to changes in their direct environment, so they need a bit more security around their blood supply to keep themselves