Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because
A) the endothelium of CNS capillaries forms a blood- brain barrier.
B) the neurolemma is impermeable to most molecules.
C) ependymal cells restrict the flow of interstitial fluid between the capillaries and the neurons.
D) astrocytes form a capsule around neurons.
E) oligodendrocytes form a continuous myelin sheath around the axons.

Question

Quizplus · Accepted Answer

The blood-brain barrier, formed by the endothelium of CNS capillaries, restricts the passage of substances from the bloodstream to the brain, protecting neurons from potentially harmful chemicals.

Many Medications Introduced into the Bloodstream Cannot Directly Affect the Neurons