Now you're using the body's metabolism to explain the metaphor to explain the body's metabolism. I don't think it's supposed to work that way. :) To highlight some of the difficulties:

So, insulin shock is the specific heat of water and/or the heat of evaporation? Does fire "slam into" the water?

As a technical point, there's a distinction between heat and temperature. The fire does not need to be "hot", it just needs to have enough heat to evaporate some of the water on the new wood, and of course hot enough to catch the wood on fire. At that point the reaction becomes self-sustaining.

I don't know how to apply that heat/temperature distinction to the metaphor.

If the "fire is out" then what are we using to survive?

(These are rhetorical. I think I know the point you're trying to get across.)

Also, what does a "perfect machine" have to do with anything? Surely not from a thermodynamics viewpoints. I can't think of anyone who thinks of the human body as a perfect machine, and I have a hard time thinking of what that would even mean.