Switching icons upon slide up & down

What I'm struggling with is this...

I would like to have the icon that I hit (makes the div toggle up & down) to switch images when being up and being down(hide).

would I need to append the icon images in javascript within the line ?
or am I no where near?

$(document).ready(function () {
/* $("ul.menu_body li:even").addClass("alt");*/
$('img.menu_head5').click(function () {
$('.entry2').slideToggle('slow'); <--- here?


});
});