Question

Name one example of a substance that CAN cross the blood-brain barrier and one example of a substance that CANNOT cross it. Be sure to indicate which is which in your answer.

Answer 1

Glucose can cross the blood-brain barrier, while white blood cells cannot.

Step-by-step explanation:

One example of a substance that can cross the blood-brain barrier (BBB) is glucose. Glucose, a vital energy source for the brain, is transported across the BBB through specialized glucose transporters.

On the other hand, an example of a substance that cannot easily cross the blood-brain barrier is large molecules such as most proteins and some drugs. The BBB is selective and restricts the passage of larger molecules to protect the brain from potentially harmful substances.

While certain mechanisms exist for the transport of specific nutrients and molecules, the blood-brain barrier acts as a highly regulated barrier to maintain the brain's microenvironment and prevent the entry of harmful agents.