Sorry Gl1tch, bob is right with the base HP, if you want to name the 1 hp a photon has let's call it starting HP.
if it has 1/1, and then you bless it, it will become 4/4, with 4 hp, If I decided to deal 3 damage to it with fire lance, it would be 4/1, but it's base hp would still be 4, because it can be healed back up to that. Playing another blessing would increase it to 7/4, but the base hp would be 7.