All of the scientific details that are involved in Ewim's Verse. All professions or situations involving science.
Caloratory System Edit
(calor [meaning "heat"] + -atory [meaning "relating to or connected with"; "representing thing or place where it happens"])
copied from Omi Smith
The thing that fuels the fire is actually an artery-like structure that is in the very core of their spine, surrounded by the white and grey matter that make up the central nervous system. It links their brain to their tail, making them co-dependent. If they are brain-dead (even if the body is “alive”), the fire goes out. If the fire goes out, the brain shuts down and goes brain-dead. I think that the fire would supply a signal to the brain that stops the “self-termination” process. So, getting rid of the fire stops that signal, which causes the “self-termination”. This already happens in humans, though not this extreme. It’s called “programmed cell-death”. Therefore, any severe damage to their spine not only threatens to cripple/paralyze them, but if bad enough to sever it, can kill them.
I imagine that the artery is strongly reinforced, covered in minuscule scales made of a strong, refined metal. Metal is already found as molecules in blood and in the brain fluids, so it is not completely outside the realms of possibility. Also, since it feeds the fire, it is very possible that the entire inside of this artery is super-heated, making the metal completely free of impurities and thus stronger. The metal would probably be one of the strongest in the world with an astoundingly high melting point, sine it can endure the heat of the fire. This, I think, gives it the potential to be reasonably well protected along with possible.
I dunno what is pumped to the tail for the fire to burn. Or perhaps it works in reverse? The fire feeds off the environment and pumps warmth and power throughout the body? I think a combination of both options could also be true.
[For non-science people, a portal system is when an artery splits again and again and again until you have this mesh-work of capillaries before they all rejoin to make a vein. It is here where a lot of stuff gets switched out, such as in the liver, where the blood dumps all sorts of stuff off and thereby filtering the blood.]
So there can be one of these at the tip of the tail, where the blood drops of the stuff being burned (like sugars, proteins, and hormones [hormones cuz the fire changes with emotions and emotions are influenced by hormones and visa versa]. Also, it could be a second place for their body to filter out bad stuff, like alcohol, poison, or viruses. Just throw it all in the fire. Actually most of that would burn in the liquid, since it is super-heated. Don’t worry, the walls of the fire system would insulate it enough to prevent harm to the Charizard as it distributes the warmth, though the liquid itself remains very hot).
I imagine that the system would be located around and inside some sort of fire organ that works like a biological furnace, thus making the tail fire a side effect of the actual thing keeping the Charizard alive. However, since it is slow close to it, extinguishing the fire would also extinguish the furnace. (This also explains why the fire can still exist for a small time in water, like in the anime. Since it is possible that it might be a some sort of oil or something being pumped, water wouldn’t be too immediately effective in putting it out, right? Does that make sense?).
In return, the blood is filtered and distributes the warmth of the fire throughout the body, thus helping with homeostasis. Power wise, I’d imagine smaller organs, like the lymph nodes of the immune system or sweat glands, placed near the skin, with tiny pores branching to the surface. There’d be dense clusters of them where ever fire is usually used, like the mouth and throat for fire breathing, though they can be generally be found throughout the body. These little fire nodes will convert the liquid (it ain’t blood, since it is not actually the circulatory system) back into fire at the Charizard’s will to use as an attack. There are substances that burn when making contact with oxygen, so it could be similar to one of those.
This would also mean that this fire system would branch off everywhere, like the circulatory system, probably right next to the immune system, where it can pick up all the stuff out of the blood and distribute the warmth and liquid throughout the body. Which is why a cold Charizard is so unnatural. If a Charizard is cold, the fire is not burning properly, thus severely compromising their immune system as well, since all the bad stuff like bacteria, parasites, and viruses are thrown into the fire. Cold Charizard = a dead Charizard, eventually. Or even worse, the fire is incapable of producing enough of the brain signal to stop the self-killing. It would be like freezing to death for them, even if the environment makes that impossible. Relatively painless but terrifying. Ice beam would be very bad, like in the anime.
To pump this fire liquid around this fire system, there would need to be a pump. Maybe Charizards have two hearts? Or a really complex 6 chamber heart, that is similar to human hearts. The heart would be just like ours but twice as thick. Imagine 2 hearts sharing one side together, but closed off completely from the other. The fire heart would only have one atria and one ventricle (which is why I said 6 and not 8. There is no reason for this fire heart to pump into the lungs). It would be fused with the right atria and right ventricle of the circulatory heart and pump in time with them, thus giving the fire system the ability to be wide spread.