function changeImage(factor)
{    
    hide(currentImage); 
    hide('_heading_' + currentImage);    
    hide('_description_' + currentImage);
                
    currentImage = currentImage + factor;
    
    if (currentImage < 1)
        currentImage = imageCount;
    else if (currentImage > imageCount)
        currentImage = 1;
    
    show(currentImage);
    show('_heading_' + currentImage);    
    show('_description_' + currentImage); 
}