A 26-year-old kindergarten teacher comes to the ED with rapidly increasing weakness. She notes that a few weeks ago, she felt “run down” with a flu, but over the past 2 days she has become very weak;...

A 26-year-old kindergarten teacher comes to the ED with rapidly increasing weakness. She notes that a few weeks ago, she felt “run down” with a flu, but over the past 2 days she has become very weak; what began as tripping over her feet evolved to trouble with stairs and now she has difficulty with any walking. Her exam is notable for areflexia of the lower extremities. Which of the following structures is impaired in this patient?

A. Axon hillock

B. Nodes of Ranvier

C. Axonal ion channels

D. Oligodendrocytes

E. Schwann cells