<span class="pull-right clickable panel-collapsed">
<i class="glyphicon glyphicon-chevron-down"></i>
</span>

if ($(this).hasClass('panel-collapsed')) {
            // expand the panel
            $(this).parents('.panel').find('.panel-body').slideDown();
            $(this).removeClass('panel-collapsed');
            $(this).find('i').removeClass('glyphicon-chevron-down').addClass('glyphicon-chevron-up');
        }