I think the name "Bitcoin" is confusing, because the system doesn't really have coins — it has addresses and transactions. Money just flows from the output(s) of one transaction to the input(s) of another. BTC can be arbitrarily divided by creating a transaction with multiple outputs; one is the payee and one is change going back to the payer. (I apologize that that probably makes no sense; I think you really have to read Satoshi's paper to understand it.)