This question is most likely just due to a misunderstanding the human body, but how come when my lungs expand, and air rushes in to fill the void, I only feel the suction above my trachea? There’s air at the same pressure below my trachea opening, isn’t there? And there’s gases that are not air inside my stomach, right? Someone set me straight.
In: Biology
You probably know that turning someone upside down doesn’t result in the contents of their stomach just falling out their mouth, right? This is because of the same kind of mechanism that keeps poop just falling straight out your butt; there are sphincters, rings of muscle that close off our digestive tract. There is one such sphincter between the esophagus and stomach that keeps the contents of the stomach, including gasses, from moving up the esophagus. If this leaks a little then the acidic contents of the stomach can irritate the esophagus in something called “acid reflux”.
Breathing works by creating a vacuum in your lungs. Your diaphragm, a muscle below your lungs, contracts to pull and expand your lungs downwards, creating negative pressure inside of your lungs. The suction comes from your lungs, so that’s where the air goes. It doesn’t go into your stomach because your stomach isn’t creating suction. Your esophagus, the tube your food goes down, is also sort of flat and flaccid, unlike your teacher which is open and rigid, so there’s not really an open pathway for air to flow into. It is quite common to get air in the stomach when someone is being manually ventilated with a bag-valve-mask because you are forcing air into the oral and nasal cavities and some will enter the esophagus.
Same reason why you can’t swallow and breath at the same time… when your trachea opens your esophagus closes, and vice-versa.
At the back of your throat there is a valve called an epiglottis. It’s situated where your Trachea (where your air goes into your lungs) and your Esophagus (where food goes to your stomach) split. It acts as a valve so food or liquid doesn’t go into your lungs. When you breathe, the diaphragm and the rib muscles act to expand your lung region, creating suction, pulling air into your lungs. The reason air doesn’t go into your stomach when you breathe is because there is no suction pulling air into your stomach. The other thing that prevents air from entering the stomach (and stomach fluids from going back up the esophagus) is the sphincter at the top of the stomach. This sphincter is why acid reflux (GERD) is a problem, it can get eroded away by constant contact with stomach acid.
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