Does it? The blood-brain barrier lets lots of stuff pass, primarily restricting large molecules and hydrophilic molecules. Some, like glucose for instance, ar

Does it? The blood-brain barrier lets lots of stuff pass, primarily restricting large molecules and hydrophilic molecules. Some, like glucose for instance, are specifically pulled through. I would expect amino-acid monomers would go right through. Prions, misfolded proteins consisting of many monomers, certainly manage to pass through, or no one would ever get the associated diseases.