Reasons why spontaneous human combustion is impossible?

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    • #17665
      Coelacanth
      Participant

      I received this question (not exact wording) on an assessment in relation to metabolism and the ETC. I found it odd, but it was a legitimate question with 6 marks if answered most accurately. I’ve given my own reasons but I would like to hear yours.

    • #114814
      1357
      Participant

      1. The heat our bodies generate is not enough to cause combustion.
      2. We don’t have chemicals (as I know) in our body that can cause sudden combustion.
      3. We are more than 60% water- and like I stated, our body heat is not so much.

      • #118197

        Yo ATP is generated during cellular respiration that is managed by the mitochondria. Through the Electron Transport Chain, 32 ATP is created from ADP and if we make too much of it we would burn up and idk what that would look like but it’s kind if not “spontaneous human combustion”.

    • #114818
      Coelacanth
      Participant

      Thanks, for the 1st reason, could there be any metabolic runaway? I’d like to know what would happen if this were to theoretically occur.

    • #114822
      jonmoulton
      Participant

      It would be interesting to calculate the energy released if all the body’s nucleotide triphosphates (e.g. ATP) were to simultaneously hydrolyze. I see no mechanism for that happening, but that should represent a pretty good stock of potential energy.

    • #114826
      JackBean
      Participant

      There is the H+ leakage in mitochondria (brown adipose tissue). However, human body contains only small amount of ATP at a moment, although it burns like few kgs per day (it’s produced and consumed all the time).

      I’d say the point No. 3 is very important. If you have 70 kg person, he or she contains about 42 kg of water. The specific heat capacity of water is ~4200 J/kg.°C. If that person has temperature of 37°C (of course the peripherals will have lower temperature) and the autoignition temperature would be let’s say 200°C (autoignition temperature of paper, which is the closest to human composition from the list, is over 200°C http://en.wikipedia.org/wiki/Autoignition_temperature ), that makes difference of 163°C. Thus one would need 163*42 = 6.8 kJ

      OK, here I found the body contains 0.25 kg of ATP http://en.wikipedia.org/wiki/Adenosine_triphosphate
      The MW is 507 g/mol, which means we contain about 0.5 mol. That would mean release of 15 kJ.
      Well, maybe I should reconsider my conclusions… 😀

    • #114827
      Coelacanth
      Participant

      A common explanation for SHC is a metabolic runaway or a ”short-circuit” in the nervous system, liberating heat which causes a person to catch fire. What do you say to that?

      PS. The 60% water argument is invalid. Radiators can cause things placed onto them to catch on fire, even though internally a radiator is merely hot water. Any heat will be conducted to the skin which will readily ignite as it contains little to no water.

    • #114828
      jonmoulton
      Participant

      Thank you Jack, I enjoyed riding along with your calculations. Coelacanth, your idea that the effect of water is lessened because only the skin is an issue for combustion is an interesting hypothesis. I’m not ready to expect spontaneous human combustion until I have seen reliable documentation, but the emerging argument makes a good tale .

    • #114829
      Coelacanth
      Participant

      I’d like to know if some metabolic runaway or nervous system short-circuit could lead up to SHC.

    • #114830
      Coelacanth
      Participant

      i watched a documentary on a man named baker , i forgot his 1st name but his doctor basically proved that hed not burnt from the outside in, but hed actually burned from the inside out .

    • #114831
      JackBean
      Participant

      1) your radiator argument is invalid. If something catches fire on the radiator, it’s because the water is hot. While the water in your body has 37°C and must be heated up, which requires about 7 kJ, as I calculated above.
      2) as you said, he burned from inside out, i.e. the inwards must burn first, thus it’s not question of skin only.
      3) I told you about the H+ leakage in brown adipose tissue. But that tissue is made to produce heat. Other tissues prevent that from happening.

    • #114845
      biohazard
      Participant

      As far as I know, fires caused by radiators are caused by electric radiators, not water/oil filled ones. Especially the water-filled radiators rarely cause fires, since the water is typically far below 100C and even if it were boiling, the pipes would burst rather than cause fire anyway. Or am I missing something here, can you really ignite things with a hot water radiator?

      I am not aware of any neural short-circuit mechanism that could cause fire, because a) the energies in the nervous system are so small that you probably could not ignite even gasoline with that and b) the human body lacks good material for burning, mostly because we are so "wet".

      My best guess for something that could be mistaken as a spontaneous human combustion would be a discharge of static electricity on some highly flammable material that would then cause the person to catch fire as well. Though that would probably not be technically SHC.

      I have always been under the impression that SHC is a persistent urban legend.

    • #118189

      I think it is possible. With enough research we may be able to use this to our advantage in the future.

    • #118191

      LOL

    • #118193

      Ya this is a very very old website lol…hehe

    • #118216
      fredrickk655
      Participant

      yes you are right .. I was surprised too

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