5 ms·

One thing I always wonder is what exactly does HCl dissolve in the stomach, and how does it not destroy the nutritional value of the food?

• kimmik 4y ago
  Low pH is needed for pepsin to work. Also to kill some pathogens. Doesn’t affect nutritional components of ingestion eg amino acids, vitamins and lipids.
  • agumonkey 4y ago
    makes me wonder what makes pathogen survive our stomach acid bath
    • altgeek 4y ago
      https://en.wikipedia.org/wiki/Helicobacter_pylori https://en.wikipedia.org/wiki/Helicobacter_pylori
  • adrian_b 4y ago
    The animals which are scavengers have more acidic stomachs than those which eat live prey, and the latter have more acidic stomachs than those which are herbivores. This is consistent with the supposition that low pH is needed to kill some pathogens. An interesting fact is that humans have a stomach pH in the scavenger range. This is consistent with the supposition that, before becoming the most successful hunters of this planet, for a long time humans had been mainly scavengers, who scared the other scavengers and predators by throwing sticks and stones, and then consumed completely the leftovers by breaking the long bones and the skulls with stones.
• bell-cot 4y ago
  > ...and how does it not destroy the nutritional value of the food? Acids destroying whatever they touch is mostly a "kiddie" version of reality. 99.9% of acids found outside of chemistry labs and industrial settings are no more dangerous or destructive (as acids) than soda pop, lime juice, or human vomit (all of which are acids). The reason is that some far stronger and/or more dangerous acids occasionally show up in household settings. Example: "battery acid", splashed on the skin, can cause horrific & life-long damage in seconds. Teaching kids to stay far away from anything labeled "Acid" is kinda like teaching 'em not to play with fire.
  • thaumasiotes 4y ago
    > 99.9% of acids found outside of chemistry labs and industrial settings are no more dangerous or destructive (as acids) than soda pop, lime juice, or human vomit (all of which are acids). > The reason is that some far stronger and/or more dangerous acids occasionally show up in household settings. Example: "battery acid", splashed on the skin, can cause horrific & life-long damage in seconds. I had to look up "battery acid"; turns out it's sulfuric acid, which is well known to be very dangerous. Of course, so is hydrochloric acid, which is the acid in human vomit. The destructiveness of the solution is not determined by the acid -- we use HCl because it is extremely destructive! -- it is determined by the acid's concentration. Note that vomiting more than a normal amount (say, because you're bulimic) will cause noticeable acid damage to your teeth.
    • bell-cot 4y ago
      > "The destructiveness of the solution is not determined by the acid [...] it is determined by the acid's concentration." I'd say you're at the "know enough to be dangerous" phase. The destructiveness of concentrated H2SO4 (sulfuric acid) to flesh is at least as much due to its extremely exothermic hydrophilic behavior as to its low pH. Hydrofluoric acid is typically weak (pH-wise) as an acid, but is a horrific delayed-action contact poison. Concentrated nitric acid is a dangerously powerful oxidizer, or worse. Yet concentrated phosphoric acid is arguably less dangerous than propane. [DISCLAIMER - Neither HN nor I are in any way responsible if you pop any statement in this item your empty little head, and head off in search of your very own Darwin Award. If you have no professional safety training in handling dangerous and/or highly-concentrated acids, then you should completely avoid them.]
      • thaumasiotes 4y ago
        I'm struggling to see the relationship between my comment and your response. For example, you emphasize pH heavily, but I don't see that I mentioned it anywhere. Hydrofluoric acid will have all kinds of horrible effects on you, sure, but it can only have those effects if it's there. Whether it's there, and to what degree, is exactly what concentration measures. Aqua regia's ability to dissolve gold is unrelated to its pH. Does that mean it can't dissolve gold? Why bring up pH? What point are you trying to make in response to the observation "99.9% of acids found outside a lab may be no more dangerous or destructive than human vomit, but that isn't particularly meaningful since the acid in human vomit is highly dangerous and destructive"?
• pjc50 4y ago
  The nutritional value is things that don't react with HCl at low concentration, especially amino acids.
• hammock 4y ago
  No one has provided the actual answer yet. Here it is- The gastroduodenal epithelium (stomach surface) is covered by a sticky mucus layer into which bicarbonate is secreted by surface epithelial cells. This bicarbonate-mucus layer creates a pH gradient with a near-neutral pH at the epithelial surfaces in stomach and duodenum, providing the first line of mucosal protection against luminal gastric acid. We only learned this in the last 20 years so it’s relatively new science Edit: either I misread the question or it was edited
  • agumonkey 4y ago
    Got to learn about tooth development, and the fact that our cells secrete apatite to then accrete into enamel. Quite mind blowing the diversity of stuff our cells can emit.