executing bash function with shell-command

[mvar]

Hello,

Apologies if this has been asked before, i couldn't find something relevant
in the archives!
I've been trying to setup a lisp function in emacs (24.5.1)  that executes
an external bash function defined in my .bashrc file (or even .emacs_bash).
If i open the shell directly from within emacs and type the function in there
it works, but if i call it with "shell-command" i get a "command not found" 
error.
A workaround is to run shell-command with "source ~/.emacs-bash && 
function_name".
Am i doing something horribly wrong?

another question, is it viable to create some function/script in Lisp
that for example will ssh to a remote machine, execute some pre-defined
commands and log-off ? The only relevant info i've found so far is for
remote editing with tramp.

thanks,
Michael