Blood-brain barrier permeability

The blood-brain barrier is a protective system of specialized blood vessels that tightly controls what substances can enter the brain from the bloodstream. Its permeability refers to how easily molecules like nutrients, medications, or harmful substances can pass through these vessel walls. While it allows essential nutrients and oxygen in, it blocks many other substances to keep the brain stable and safe. Factors like inflammation or disease can change this permeability, making the barrier more or less selective, which impacts brain health and the effectiveness of certain drugs.