Well i think its more like the muscles and organs "need" chakra to work in the first place... since the heart generates it its very likely...Originally Posted by Uchiha Barles
So if the user drains chakra from his muscles and organs, he will suffer heavy damage, from the side effects
Ya, this way if someone uses up all of his chakra, he will die, because his organs, muscles simply everything, will stop functioning.
Thats what I believe is the case.
I think medic-nins infuse chakra to the victims they want to heal.. this is could be wrong though... but well, it does LOOK like they do it ^^
The cells use the extra amount of chakra, provide by the medic, to regenerate themselves faster etc.