What brain defense restricts substances from entering the brain by the vascular system?

Question

Quizplus · Accepted Answer

The blood-brain barrier is a protective mechanism that restricts substances from entering the brain by the vascular system. It is composed of tightly packed cells in the walls of the capillaries that supply the brain, and it helps to prevent harmful substances and pathogens from entering the brain tissue. The meninges, macrophages, microglia, and cranium are all also involved in protecting the brain, but they do not specifically restrict substances from entering through the vascular system.

What Brain Defense Restricts Substances from Entering the Brain by the Vascular