Nokea
When an action potential reaches the axon terminal, what happens next?
Correct Answer: c
Rationale: The correct answer is C because when an action potential reaches the axon terminal, endosomes containing neurotransmitters fuse with the cell membrane and release neurotransmitter into the synaptic cleft. This process is known as exocytosis. This neurotransmitter then binds to receptors on the postsynaptic neuron, initiating a new action potential.
Choice A is incorrect because the muscle fiber contraction is initiated by the binding of the neurotransmitter to receptors on the muscle cell, not directly by the action potential reaching the axon terminal.
Choice B is incorrect because acetylcholinesterase breaks down acetylcholine in the synaptic cleft after it has already been released and has completed its role in transmitting the signal.
Choice D is incorrect because sodium channels opening at the motor end plate is part of the process of muscle cell depolarization and contraction, not directly related to the release of neurotransmitter at the axon terminal.