The Esophagus: An In-Depth Look at Its Function and Importance

For many people, the esophagus is a tube that starts somewhere in the back of your throat and ends at your stomach, and through which you carry all your food and drinks. That’s it.

After twenty years of research, gastroenterologist Sheila Krishnadath (Antwerp University Hospital) knows better. As a professor she specializes in the esophagus. ‘When you take a sip, it doesn’t just go down through the esophagus. The esophagus is very actively involved in this.’ But why isn’t a simple chute sufficient?

Gravity is not enough

It seems simple: what you eat ends up in the stomach. It’s under your throat, so let gravity do its work and you’re done. That’s too simplistic. What is in your stomach cannot be returned to your mouth. If you are lying down or upside down, up and down are no longer clear. Even then, things should not come up (well, down).

In addition, the esophagus must be prepared for intruders, says Krishnadath. ‘She is the first part of your intestines that has contact with everything that comes from outside. That is intense, because all kinds of things come in that you need to be protected against.’ With food you also swallow harmful substances, bacteria and viruses. These can be dangerous once they leave your esophagus. That requires ingenious management.

The esophagus is not a hollow, open tube

An esophagus looks different than you probably imagine, says Krishnadath. “It’s not a hollow, open tube.” When it is empty, the tissue lies against each other. ‘When you investigate with a camera, you see that the esophagus is compressed. The airway is open because you breathe constantly, while you only eat occasionally.’

Only when food or drink arrives does the esophagus open, thanks to muscles in the wall. ‘Then the larynx covers the trachea to prevent food from entering it. That is a very nice mechanism: literally a flap that covers everything.’

Kneading and pressing

Once access to your intestines is clear, the real work begins. ‘Your esophagus makes a peristaltic movement: food gradually enters your stomach in a wave movement.’ Just as you watch an eaten rat slide through the belly of a snake, a bite of food slides down, Krishnadath explains. Even a sip of tea doesn’t hit your stomach right away, but only after a few seconds of belly dancing.

‘The lining of the esophagus has a beautiful mother-of-pearl shine’

During that journey down, hazardous substances and bacteria must be kept under control. They shouldn’t escape before your stomach’s acid can take care of them. The solution to that problem was a clever copy of the esophagus from another part of the body, says Krishnadath. ‘How do you keep the rest of your body safe? You have skin for protection for that. The lining of the esophagus is very similar to our skin. If you look into the esophagus, you see a very beautiful mother-of-pearl surface.’

Just-not-real skin on the inside

Just like with the skin, multiple layers of flat cells make it almost impenetrable. The relationship with the skin is even clearer in some genetic disorders. Then hairs can even grow on parts of the esophagus.

The inside of the esophagus is not identical to the skin. It’s quite a mess there. Mucus from our throat and nose slides down through the esophagus, but the intestine itself also produces an extra slippery layer with mucus cells in the wall. This lubricant helps food slide more easily into your stomach. Bacteria are also less likely to damage cells due to this layer.

Lock the acid in with muscle power

Once food arrives downstairs, it must stay there. Because the acid in your stomach is not only harmful to invaders, but also to your esophagus. Just like at the top, there is a closure at the bottom. ‘There is a muscle around the esophagus that ensures that it remains closed at the bottom. It is not a valve that you open and close, but a muscle that can press everything closed.’ This prevents food from bubbling up in your stomach.

Showing pathogens the door

Not unwanted at least. Because sometimes things have to go back up again, and quickly. In case of illness, vomiting helps to get possible pathogens out of the body as quickly as possible. The esophagus then plays a supporting role, says Krishnadath. He opens the gates and the peristaltic movement now goes the other way. But it is mainly your stomach that does the heavy work. It contracts with great fanaticism, causing the stomach contents to squirt out at the top. It is not the nicest experience, but it is one of the many moments when your esophagus proves its usefulness.

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2024-02-16 16:51:47
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