Which of the following compounds cannot cross the blood-brain barrier?
A) Water
B) Carbon dioxide
C) Glucose
D) Dopamine

Question

Quizplus · Accepted Answer

Dopamine cannot cross the blood-brain barrier due to its large, polar structure. The blood-brain barrier is highly selective, allowing only certain small or lipid-soluble molecules like water and carbon dioxide to pass freely. Glucose can cross through specific transport mechanisms, but dopamine requires active transport or modification to cross.

Which of the Following Compounds Cannot Cross the Blood-Brain Barrier