How to make Animated GUI element.

I tried searching for a very long time now, Im trying to do the lifeline system of resident evil 3. (The little medic bar, that turns green when you are fine, yellow in caution, and so on, when the inventory is open.)

Im guessing I need the images for that, and they need to animate accordingly to the player health, but, how do I put them in action? how do I animate them? I know how to do everything except animating those.

(NOT SLIDER TYPE HEALTH BAR OR RELATED, I already have that system and want to change it to something like this:.)

Thanks, in advance :)