Dopamine is in an organ.
In the brain , dopamine functions as a neurotransmitter -- a chemical released by neurons -LRB- nerve cells -RRB- to send signals to other nerve cells .	brain	brain	neurotransmitter	neurotransmitter
The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals .	organ	organ (anatomy)	nervous system	nervous system	vertebrate	vertebrate	invertebrate	invertebrate
