If our stomach acids are some of the strongest acids, how do stomach bugs and tapeworms and germs not get digested in it? How is it that only things like insulin get digested?
In: Biology
Parasites generally don’t come into your system as full-grown organisms. What happens is that you consume either their eggs or cysticerci (cysticerci are sort of like eggs, but are found in the muscle of pigs or cattle in the form of cysts). Both of these are resistant to digestion; both acidic and enzymatic. Once the eggs or cysticerci pass through your stomach and end up in a more favorable environment in the small intestine they will hatch and grow into proper parasitic organisms like tapeworms, roundworms, pinworms, etc. I encourage you to google images of human parasite lifecycles to get a nice general idea.
A lot of the bacteria and the tapeworms/parasites reside in your intestinal tract. After food leaves your stomach and enters the small intestine, the acid is neutralized in the duodenum with a bicarbonate secreted by the pancreas. So by the time it hits your intestines, the food is broken down but no longer acidic.
3 things.
1. Strong acids are dangerous and dissolve things that usually don’t dissolve in water, but it’s untrue to say that strong acids dissolve even most things.
2. Stomach acid doesn’t even do most of the digestion. Most of what the acid in your stomach does is make the conditions for certain biological enzymes to work. These enzymes break down some biological materials.
3. Like the other comment said, lots of the germs/parasites that are consumed are digested, but the ones that aren’t get you sick
The thing is – you’re eating stomach bugs and germs constantly, but the vast majority of them do get digested. It’s only certain things that resist it well enough to be a problem. For example, h. pylori is a bacteria that likes to infect your stomach and cause ulcers, and has ways of modifying the inside of your stomach to suit it.
Most of the answers here don’t address the question. The number 1 reason is that you ingest the cyst form of the parasite, which is dormant and highly resistant to all environments. Once it gets to your intestines it will grow into a trophozoite which is the full grown organism.
In addition, man bacteria create toxins on the food *before* you ingest it. The bacteria will die in your stomach but the toxins will still exert their effect.
Just as your stomach doesn’t digest itself, a tapeworm egg or other bug may have a protective coating of some kind that allows it to survive its time in the stomach until it makes it to your intestine.
It can’t survive indefinitely in your stomach, but if it is only there for a short time, it will make it through.
Other bugs are totally happy in your stomach. Your stomach is actually full of bacteria (generally ‘good’ bacteria). So there are some that are just able to produce lots of substances that help it survive in the acidic environment.
Life, uh, finds a way.
How come your stomach does not get digested? How come corn (if not bitten through) will not get digested and just pass through the system (ever notice corn kernels in your poop?)?
They have protective layers. Bacteria with protective layers can survive stomach acid too (helicobacter pylori, causes stomach ulcers). Protective layers everywhere.
That’s why it’s also important to chew plants – they have a protective coating on the outside, so you need to mush them with your teeth to mechanically destroy (or cause holes in) the protective layer to let the acid dissolve it further.
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Most people overestimate the amount of your digestive system that involves acid.
Generally “gut” parasites get into you as eggs, which have protective coatings much like your stomach lining does.
Once they pass through the stomach, they actually develop and live in the intestines, which are designed to much more slowly and gently break down foods that have already been chewed and then weakened by saliva and stomach acid using enzymatic and bacterial action. It’s a much easier place for something to adapt to and we actually have a ton of bacteria in there that helps us breakdown food. Parasites are larger and less durable than extremophile bacteria can be, but the specialists like tapeworms are still plenty tough enough to survive the (relative to the stomach) gentle environment of the intestines.
Tapeworms and germs developed coatings and protection to get past the stomach acid. The acid is neutralized after and in the intestines is where the bugs and germs go to work destroying you. The stomach the a little larger that your fist, its the intestines that most people think of as your guts.
Also, insulin isn’t digested, it’s injected.
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