Many medications introduced into the bloodstream cannot directly affect the neurons of the cns because a) oligodendrocytes form a continuous myelin sheath around the axons. b) the endothelium of cns capillaries forms a blood-brain barrier. c) the neurolemma is impermeable to most molecules. d) ependymal cells restrict the flow of interstitial fluid between the capillaries and the neurons. e) astrocytes form a capsule around neurons. b extensive damage to oligodendrocytes in the cns could result in

B. the endothelium of CNS capillaries forms a blood-brain barrier

Explanation:

Commonly known as the blood-brain barrier or BBB is formed by the action of endothelial cells of brain which line the cerebral microvasculature. The BBB is a vital mechanism that protects the brain from the action of many circulating agents which are present in different medications like xenobiotics or other neurotransmitters which can disrupt the neural functions or harm them. The BBB also functions to protect the brain from the fluctuations in plasma composition of brain cells.

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it's c. (to reduce the greenhouse effect/carbon gasses)

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.