General

The blood-brain barrier

The brain is a highly vulnerable organ. That is why it is protected by a sturdy skull. On the inside, the brain is also well protected against harmful invaders like bacteria and viruses.

The blood vessels in the brain are therefore different from those in other organs. The cells in the vascular walls are packed together more densely, in order to give better protection. This protective wall is also called the blood-brain barrier. It prevents viruses and bacteria from entering the brain.

Oxygen can easily penetrate this barrier, however. So can drugs.