Neurotransmitters

We know that transmission of signals from nerves to muscles is affected by acetylcholine a transmitter substance. Similarly neuron-neuron transmission is also achieved by acetylcholine. But there are several other chemicals that function as neurotransmitters. A limited number has already been identified and new ones are being identified rapidly.

A chemical can be called a neurotransmitter in a given tissue only if it fulfils certain conditions like:

1. When applied to the postsynaptic membrane it should be able to produce the same effect as does presynaptic stimulation
2. It should also be released by the presynaptic membrane
3. Its action should be blocked by the same agents that block neural transmission.