Eli5 How does food and liquids remain inside the stomach and not “leak out of your mouth” whilst being in space?

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Eli5 How does food and liquids remain inside the stomach and not “leak out of your mouth” whilst being in space?

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Anonymous 0 Comments

Most of us have a vision of the stomach that was shown to us in TV and cartoons – a big cavernous space with a big hole in the top and a pool of acid in the bottom, where everything we eat comes flying out of the hole and crashes into the acid pool with a big splash.

In reality, our body doesn’t really have any big empty spaces, but everything squished up together. So rather than the big cavern, our stomach is more like a water balloon full of acid with a knot holding it shut. When we eat something, it is pushed down your throat by the muscles that make up your esophagus (for a good example, see if you can find a video of a snake eating something really big and watch it get pushed along its body).

At the top of the stomach there is a muscle that holds it shut like the knot of the balloon – it opens up just enough to let the food be pushed inside, then closes up again before anything can escape.

Inside it is completely full of stomach acid and whatever you have eaten, with no air – sometimes gas will be produced (like when you consume a fuzzy drink), which the muscle at the top quickly and carefully let’s out in the form of a burp.

At the opposite end, there is another muscle controlling what is let through into your intestines in the same way.

So to answer the original question, when laying down, upside down or in zero gravity, the muscle between the esophagus and stomach acts like a door, only opening to let food through when it wants to, otherwise closing up to stop food flowing back up your throat as you dangle upside down.
And because everything is squished in together and solid without big air pockets, it doesn’t really slosh around quite like you would expect, but just stays in place

Anonymous 0 Comments

There is a sphincter valve at the top of your stomach where it connects to the esophagus. Normally unless swallowing (or in case of dysfunction , which can cause acid reflux for example) it is closed and prevents food from emerging even when hanging upside down, for example.

Anonymous 0 Comments

Literally, the same reason why you don’t shit yourself.

See the anus is a ring muscle, called sphincter, you have one of those at the entrance and exit of your stomach, and anotherone that separates the small and large intestines.

Anonymous 0 Comments

A lot of answers here but none of them admit, yes, sometimes it does leak out in space. We have natural rings of muscle that close things off, that’s why you don’t just vomit if you bend over at the waist on earth.

However..food and liquids don’t really remain in the stomach in space. If you burp in space, you will likely also push out stuff in your stomach. (There is no gravity ensuring the lighter, burped gases are the only thing at the top of your stomach.)

Anonymous 0 Comments

If you really want to blow OP’s mind, tell him about [peeing upside down](https://www.reddit.com/r/NoStupidQuestions/comments/c21h5j/can_you_pee_upside_down/erh0hg3/).

Anonymous 0 Comments

The same way they don’t leak out of your mouth when you do a handstand, or lay on your stomach. You have muscles that keep things in place.

Anonymous 0 Comments

All good answers and just reaffirming this is not a dumb question, humans and other mammals have a series of “valves” and muscles that keep pushing the food actively from the mouth to the butt.

Birds, for example, don’t. They need gravity to swallow and do the work. Hence why we sent monkeys, apes, and dogs into space to test early space ships and not smaller, easier, or cheaper animals.

Anonymous 0 Comments

Your stomach has muscles around the opening to keep food inside. Thus why you aren’t vomiting stomach acid when performing a hand stand or otherwise upside-down. Furthermore, muscles around your esophagus will actively push food down towards the stomach in a process called peristalsis, allowing you to properly swallow and eat regardless of orientation or if floating around in space.

Anonymous 0 Comments

Short answer? Sphincters.

Anonymous 0 Comments

There is a muscle at the top of your stomach. It is a ring that holds closed unless you are swallowing or puking. This is why you can be upside down and won’t have what’s in your stomach pour out. Same thing as why you don’t pee yourself each time you stand as there is one right at the exit of your bladder. These types of muscles are all through the body and control the flow of liquids.