Neurophysiology and Synapses · USMLE Step 1

Which of the following best describes “graded potentials” in neurons as opposed to action potentials?

  1. They are all-or-none events that propagate along the axon.
  2. They vary in magnitude and decay over time and distance.
  3. They always trigger neurotransmitter release.
  4. They are mediated exclusively by voltage-gated sodium channels.
Show answer and explanation

Correct answer: They vary in magnitude and decay over time and distance.

Graded potentials vary in amplitude depending on stimulus strength, and decrease in magnitude over time and space. They often arise at dendrites or postsynaptic membranes via ligand-gated channels, in contrast to all-or-none action potentials.

Difficulty: Medium Question 11 of 28

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