What is acid reflux? The acid from the stomach comes back up the esophagus, causing a lot of pain and sometimes even damage.
Most animals that have a stomach that digests their food produce stomach acid. The acid in our stomachs is very strong. It has a pH of roughly 2, which makes it a very strong acid. However, it is not the strongest acid of all animals. That honor goes to the vulture, which has stomach acid with a pH of 0. That is so acidic that they would be able to dissolve metal.
We produce about 4 liters of stomach acid a day and there are two reasons why we need it. The first reason is to digest food. The acid breaks up compounds in the food we have eaten. It also activates other enzymes that we use for digestion. It helps us absorb many minerals and vitamins as well. The second thing it does is to kill any bacteria or viruses that manage to make it down to our stomachs. People that get acid reflux and take medicine to lower the acidity of their stomach acid get more colds because that line of defense is not as strong. And that is the reason why vultures have such strong stomach acid. They eat food that is rotten and they are exposed to very dangerous bacteria that can survive weaker stomach acid. We get around that by cooking our food, but if you have ever gotten food poisoning, that is bacteria that can survive your stomach acid.
The stomach acid is so strong that our stomach lining and intestines need special protection so they don’t get eaten as well. There are three things that they do. The first is the cells in the stomach lining are hardier than general cells and are less affected by acid. The acid will still eat them, it just takes longer. The second thing is they produce a protective layer of mucus. This mucus has a whole host of chemicals that protect against the acid. And the third thing is the lining of the stomach and the intestines regrows every few days. The stomach acid has to pass out of the stomach and along the intestines with the food it is digesting. The small intestine doesn’t have as much protection against the stomach acid as the large intestine and the stomach. This is because the pancreas produces bicarbonate, which is a form of carbon dioxide, that rapidly raises the pH of the stomach acid neutralizing it.
The body has evolved to have a very strong acid inside its stomach and to protect itself from that acid. Acid reflux is a problem that arises when the body is no longer able to keep the stomach acid where it is supposed to be. The word “reflux” means “the flow of a liquid through a valve or vessel in the body in a direction opposite to normal.” The acid is moving in the wrong direction.
When we eat, we chew the food in our mouths and mix it with saliva, which starts digesting it. Then we swallow the food, and it goes down our esophagus. The esophagus stretches from the back of the throat all the way down to the top of the stomach. If we are upright, gravity helps get food down to the stomach, but the walls of the esophagus are made of muscle that can force the food down. The end of the esophagus has a ring of muscle called the Lower Esophageal Sphincter. This is automatically kept shut, but it opens to let food through, then springs shut again. Its job is to keep the stomach acids out of the esophagus. Acid reflux happens when, for whatever reason, that sphincter doesn’t close completely, and stomach acid can get back up into the esophagus. If this happens, stomach acid enters the esophagus and rises up. You might be able to taste it at the back of your throat. We have all had a taste of what that is like when we have thrown up.
Acid reflux can cause heartburn. It is not actually anything to do with the heart, but we call it heartburn because of the location. When the sphincter at the bottom of the esophagus fails and stomach acid goes back up, the stomach acid burns the esophagus. We think our stomach is down by our bellybutton, but it is actually much higher than that. The entrance to the stomach, where the sphincter is, is roughly behind the sternum, in the middle of the chest. The acid burns this part of the lower esophagus, which feels very much like chest pain. That is also why indigestion can be mistaken for a heart attack.
Acid reflux happens to most people at some point in their lives and it isn’t really a problem. It can become a problem if it becomes common. Sometimes, the sphincter can weaken, and acid reflux can happen a lot. In this case, it is known as gastro-esophageal reflux disease (GORD). It can be very uncomfortable. There are ways to deal with it, such as various lifestyle changes, and surgery on the sphincter is also an option. And this is what I learned today.
Photo by Anastasia Shuraeva: https://www.pexels.com/photo/man-holding-his-stomach-and-chest-8795387/
Sources
https://www.scientificamerican.com/article/why-dont-our-digestive-ac
https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=bicarbonate
https://zoe.com/learn/stomach-acid-facts
https://www.healthline.com/health/gerd/heartburn-relief#prevention
https://www.nhs.uk/conditions/heartburn-and-acid-reflux
https://www.mountsinai.org/health-library/diseases-conditions/gastroesophageal-reflux-disease
https://kidshealth.org/en/parents/digestive.html
https://www.mayoclinic.org/diseases-conditions/heartburn/symptoms-causes/syc-20373223