Normally, electrical signals, or action potentials, travel down the axon to the axon terminal, where they trigger the release of chemical messengers called neurotransmitters from synaptic vesicles into the synapse.

通常情况下，电信号或动作电位通过轴突传递到轴突末梢，从而刺激化学信号分子（神经递质）从突触小泡释放到突触间隙。

This set-up has two principal parts: The cell that's sending the signal is the presynaptic neuron, and it transmits through a knoblike structure called the presynaptic terminal, usually the axon terminal.

这种设置有两个主要部分：发送信号的细胞是突触前神经元，它通过一个叫做突触前终端的节状结构进行传输，通常是轴突终端。

The upper motor neuron releases acetylcholine from its axon terminal knobs and these are received by nicotinic receptors on the alpha motor neuron.

上运动神经元从轴突末端释放乙酰胆碱，作用于α运动神经元上的烟碱受体。

Cocaine increases the release of certain neurotransmitters, but it's biggest effect is blocking reuptake receptors on presynaptic axon terminals, and both actions keep neurotransmitters like dopamine, norepinephrine, and serotonin in the synapse longer and increases their effects.

可卡因促进一些特定神经递质的释放，但它最大的作用是阻止突触前神经元终端受体的“再摄取”；两种作用都能使得神经递质，如多巴胺、去甲肾上腺素与5-HT，在突触间隙存留时间延长，从而加强他们的作用。

In the central nervous system, nicotinic receptors are on pre-synaptic axon terminals of neurons, and when nicotine binds to them, it triggers the release of neurotransmitters like dopamine, acetylcholine, and glutamate, which is why it's considered an acetylcholine agonist.

在中枢神经系统中，烟碱受体分布于突触前神经元的轴突末端，当尼古丁与受体结合后，会触发多巴胺、乙酰胆碱、谷氨酸盐等神经递质的释放，因此尼古丁被认为是一种乙酰胆碱受体兴奋剂。