system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly are neurotransmitters and why do we need so many different types of neurotransmitters?
gpt
Neurotransmitters in short are little chemicals that our body responds to in various ways (transmitters). We add neuro because they originate and communicate across neurons. 

We have a number of different neurotransmitters based on a few reasons, what is the likely the most important reason is to send different signals to the same tissues or similar tissues; as well as to reduce “noise” from neurotransmitters escaping and activating nearby cells and neurons.