is a chemical substance released from the nerve endings that causes irritation, which leads to a reaction – muscle contraction.

Neurotransmitters are divided into:

  • excitatory neurotransmitters
  • inhibitory neurotransmitters

The best known are dopamine, norepinephrine, serotonin and glycine. At the same time, some neurotransmitters have hormonal functions and occur outside the nervous system. Their disorders cause certain neurological and psychiatric diseases, such as depression, Parkinson’s disease or schizophrenia.