why are axon terminals sometimes called "biologist transducers"?

2 answers

Study these definitions.

http://www.google.com/search?hl=en&rlz=1G1GGLQ_ENUS308&defl=en&q=define:Axon+terminals&sa=X&ei=SFW-TJnBFIP6lwe8kbTiBw&ved=0CBIQkAE

http://www.google.com/search?hl=en&rlz=1G1GGLQ_ENUS308&defl=en&q=define:transducer&sa=X&ei=e1W-TJ_2GcaqlAfqvtDUDQ&ved=0CBUQkAE

A transducer changes energy from one form to another. What happens at axon terminals?