What is a "neurotransmitter"?

What is a "neurotransmitter"?

Neurotransmitter is a chemical made by the neuron which comes down into the nerve and is released to make whatever it's in contact with activate. If the neurotransmitter is going to make the muscle contract, it would come out of the motor neuron, the motor neuron would make that transmitter. It would send it down the nerve, and it would be released by what we call vessicales. There is a cleft between what we call the pre-synaptic which is the motor neuron, in this case, and the post-synaptic, which would be the muscle. The muscle now has a receptor for that neurotransmitter. So serretonin, for instance, is a neurotransmitter and dopamine is a neurotransmitter. But what they are is chemicals made by a neuron to speak to wherever they are making contact. They release it and it makes the other cell activate. Whether it be muscle or another neuron. Sometimes it's a hormone, sometimes its a kidney, sometimes it's a blood vessel. So whatever it's making contact with, it will do it.