Question

Identify the correct sequence of action potential as it arrives at the axon terminal from the choices given below:

• A. Axon terminal $\rightarrow$ Post-synaptic membrane $\rightarrow$ Synaptic cleft $\rightarrow$ Synaptic vesicles Post-synaptic neuron
• B. Axon terminal $\rightarrow$ Synaptic vesicles $\rightarrow$ Post-synaptic membrane $\rightarrow$ Synaptic cleft $\rightarrow$ Post-synaptic neuron
• C. Axon terminal $\rightarrow$ Synaptic vesicles $\rightarrow$ Synaptic cleft $\rightarrow$ Post-synaptic membrane $\rightarrow$ Post-synaptic neuron
• D. Axon terminal $\rightarrow$ Synaptic cleft $\rightarrow$ Synaptic vesicles $\rightarrow$ Post-synaptic neuron $\rightarrow$ Post-synaptic membrane

Hint:

Synaptic vesicles release neurotransmitters into the cleft after the action potential arrives.

Answer 1

The Correct Option is C

• Synaptic Transmission: The action potential triggers neurotransmitter release at the axon terminal.
• Sequence Analysis:
  • Action potential reaches the axon terminal.
  • Synaptic vesicles release neurotransmitters into the synaptic cleft.
  • Neurotransmitters cross the synaptic cleft and bind to receptors on the post-synaptic membrane.
  • This depolarizes the post-synaptic neuron.
• Option Analysis:
  • (1) Axon terminal → Post-synaptic membrane → Synaptic cleft → Synaptic vesicles Post-synaptic neuron: Incorrect order, vesicles release before cleft interaction.
  • (2) Axon terminal → Synaptic vesicles → Post-synaptic membrane → Synaptic cleft → Post-synaptic neuron: Incorrect, vesicles release into cleft first.
  • (3) Axon terminal → Synaptic vesicles → Synaptic cleft → Post-synaptic membrane → Post-synaptic neuron: Correct sequence of vesicle release, cleft crossing, and membrane activation.
  • (4) Axon terminal → Synaptic cleft → Synaptic vesicles → Post-synaptic neuron → Post-synaptic membrane: Incorrect, vesicles release before cleft.
• Conclusion: The correct answer is (3), as it follows the proper sequence of synaptic transmission.