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MDCAT Biology QUESTION #7784
Question 1

Depolarization of the postsynaptic membrane is caused by diffusion of which ion?

  • Calcium ions
  • Chloride ions
  • Potassium ions
  • Sodium ions✔️
Correct Answer Explanation

Depolarization occurs when Na⁺ enters the postsynaptic neuron (excitatory postsynaptic potential). Cl⁻ influx causes hyperpolarization (inhibitory). Ca²⁺ triggers neurotransmitter release, not directly depolarization.