The Human Question

I wonder how the metabolism of a neural cell is related to its receiving and transmitting neurotransmitters: is there something meabolic about neurotransmission?  I know that the neurons metabolize nutrients that are in no way neurotransmitters, but I am asking something different here... about how the cells are related to neurotransmitters.  That is, at some crude level of understanding, one might say that the neurotransmitters are "ingested"; but they don't function as nutrients in the cells that receive them.  They instead function as....triggers?   That said, is there more of a similarity than one might point out by making an initial crude comparison? Also, could neurotransmission be an example of how a higher function transforms lower ones... which was described as appropriation in my dissertation?