To replace the video card on a laptop what would you have to do?

people say you cant replace the video card, but I mean its attached to something, and people build laptops so im assuming one of two things which i need confirmed or denied,

could you replace the motherboard or whatever the video card is attached to, and it would still run, or would you just really have to replace the computer itself?|||..THERE IS...NO.video card in a laptop!!..the video is built into the Motherboard!!!!!!!!!!