How is synaptic strength at the neuromuscular junction enhanced?

Synaptic strength at the neuromuscular junction is enhanced through both action potentials and increased neurotransmitter release.

When an action potential travels down a motor neuron, it causes the opening of voltage-gated calcium channels in the presynaptic terminal. This leads to an influx of calcium ions which triggers the release of neurotransmitters, specifically acetylcholine, into the synaptic cleft. The presence of more acetylcholine increases the likelihood of receptor activation on the postsynaptic muscle cell, enhancing the strength of the synaptic transmission.

Additionally, if the frequency of action potentials increases, this leads to greater cumulative release of acetylcholine. More neurotransmitter release translates to a stronger synaptic response, resulting in greater muscle contraction and enhanced neuromuscular efficiency.

Consequently, both the propagation of action potentials and an increase in neurotransmitter release play crucial roles in augmenting synaptic strength at the neuromuscular junction, which is why this combination is the correct answer.