[ELI5] When you accidentally inhale something, like water or food, and you cough it mostly up and are fine, how does the rest get out of your lungs and how do you not get pneumonia?


[ELI5] When you accidentally inhale something, like water or food, and you cough it mostly up and are fine, how does the rest get out of your lungs and how do you not get pneumonia?

In: Biology

Your lungs are full of mucous. There are little hairs in your airways that push the mucous out, which picks up most of the basteria and liquid you might swallow. If you get water actually in your lungs, you can only hope to cough it out. It will evaporate over time too, but you’ll have less lung capacity in the meantime and be at higher risk of pneumonia.

If it’s not water, it may stay in your lungs forever.

Your airways are all covered with little “finger-like projections” called cilia. Their entire job is to grab onto junk that doesn’t belong and scoot it back up and out until you can cough it out. Things that don’t get pushed out like this get absorbed, ie, water, or attacked and eaten up by the many immune cells that live in your lungs.

For pneumonia to occur, you usually need a much larger amount of food or fluid to get deeper in the lungs than most people will achieve with regular choking. More likely, people who get pneumonia already have a respiratory infection interfering with a normal immune response, which allows bacteria to set up shop and go wild 🎉🎉

Edit: Thank you for awards! 😮 Wow! ☺️

So I’m a radiologist. One of the tests I do has lots of names but the most straightforward is “video swallow” which I perform with a speech pathologist.

They mix up different liquids and foods with a material called barium sulfate that shows up on X rays. You eat and drink them while I take like “video style” low dose x rays called fluoroscopy.

What we we are looking for is making sure food goes down the right pipe. Your windpipe (trachea) is in front of your food pipe (esophagus) and the windpipe has a little flap of tissue (epiglottis) that covers it when you swallow to direct food back to esophagus.

Now, sometimes your swallow muscles are paralyzed or weak. This could be from a stoke or other neurologic condition or radiation/surgery. This causes liquid or food to get under that flap and down the windpipe. Sometimes the people hack and cough (as you do when it goes down the wrong pipe) but often they may not even notice if they have a neurologic condition. This food going down the wrong pipe and beyond the vocal cords is called aspiration.

The reason I bring this up is because even when people aspirate, it’s a small fraction of what they ingest. Most still goes back. And your body does have defenses like mucous and inflammatory cells to protect your lungs. So a little tea or mashed potatoes slipping past once a year isn’t going go to do that much. However, if it’s happening with every bite or drink every meal them that DOES cause bad pneumonias.

Also, when a healthy person aspirates and hacks and coughs, you’re actually clearing out a lot of that material that went the wrong way before it’s past the cords. Maybe a drop or so falls but that causes such a reaction you protect yourself.

Note, this is a very different process to aspirated foreign bodies like pieces of a toy or hotdogs with children or when someone “can’t breath” and needs the heimlich. If you or someone you know is worried that something substantial was aspirated, seek medical attention.

If one maintains proper oral hygiene the risk of pneumonia upon aspiration of water is virtually zero. The lungs are moist. So unless the water ingested picks up a bunch of nasty bacteria in the mouth on it’s way toward the trachea it’s not a big deal.
When people suffer even severe dysphagia (aka: getting stuff “down the wrong pipe”) it’s not uncommon to implement a “free water protocol” when they are otherwise encouraged to avoid eating or drinking due to a high risk of aspiration.

The choking or “gag reflex” will get triggered when the food is still roughly in the throat area. The food would still have to go all the way down food pipe/trachea which is quite long way before reaching the lung tissue, and would be coughed up by a healthy individual before then. Some diseases affect this ability though.

just as a side point and I see it all the time. you should never throw peanuts in the air and catch them in your mouth because if they go down the wrong way and into your lungs, you may well cough it back up but the peanut oil will soak into the lung membrane like blotting paper and kill that part