Neurotransmitters: These are chemical messengers that transmit signals across a synapse from one neuron (nerve cell) to another 'target' neuron.
Reuptake: This is a process in which neurotransmitters that have not been received by the next neuron are taken back up into the sending neuron. It’s like if a post office took back any undelivered mail.
Axon: This is the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells. It's like the delivery truck that carries messages away from the neuron.