What is the mechanism that prevents or slows some chemicals from entering the brain, while allowing others to enter?

Question

Quizplus · Accepted Answer

The blood-brain barrier is a specialized mechanism that prevents or slows the entry of certain chemicals into the brain. This barrier consists of tightly packed cells that line the blood vessels in the brain, which restrict the passage of certain substances, while allowing others to pass through. This barrier helps protect the delicate structures of the brain by preventing harmful substances from entering, but it also poses a challenge for delivering drugs to the brain for medical treatments.

What Is the Mechanism That Prevents or Slows Some Chemicals