The nodes of Ranvier:
A. Are distributed approximately every 1 to 2 millimeters (mm) along the membrane of the cell axon.
B. Contain a high density of modality-gated K+ channels for rapid depolarization of the membrane.
C. Contain a high density of voltage-gated Na+ channels for rapid repolarization of the membrane.
D. Have low membrane capacitance, preventing the accumulation of electrical charge.
E. Are heavily myelinated, which allows for rapid diffusion of an electrical potential.
ANS: A
Rationale: The nodes are specialized for active propagation of an action potential by allowing ion flow across the membrane. The nodes of Ranvier are distributed every 1 to 2 mm along the axon and contain high densities of voltage-gated Na+ and K+ channels. An action potential spreads rapidly along a myelinated region and then slows when crossing the high-capacitance, unmyelinated region of the nodes of Ranvier.
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