Mini Lesson: Stomach

Video Transcript

When I was a kid, and even into to my early adult years, my understanding of digestion was pretty limited and I generally thought that my stomach was the major organ responsible for breaking down all of my food. But, today we are going to talk about what the stomach actually does.

Basic Anatomy

The stomach is this wrinkly, pouch-like structure with specialized circular muscles that control the opening that separates it from the esophagus and the small intestine. These muscles relax to allow food to pass through the opening, but should promptly contract afterward to create a barrier. It is very important for these muscles to keep the stomach’s contents separated from the rest of the digestive tract, because the stomach is responsible for releasing some very strong acids and enzymes.

Chemical Digestion

The stomach acid, and the specialized enzymes that work in the stomach’s acidic environment, are necessary to break down protein. This is really important for digesting proteins in foods, but it also breaks down the protein-based enzymes that were released in the mouth to break down carbohydrates. This means that the stomach is primarily responsible for digesting proteins and carbohydrate digestion is put on hold. There are also some enzymes that help to break down fats while in the stomach, but fat digestion is pretty limited at this point.

Protective Mucus

The stomach needs to stay mostly separated from the rest of the digestive tract because the acid and enzymes of the stomach are also capable of breaking down the proteins in the body’s own cells. To keep these chemicals from digesting our own body tissues, there are also specialized cells that make mucus to create a lining for the stomach and protect it from being destroyed by the digestive juices in the stomach.

Mechanical Digestion

The stomach can also expand to hold quite a bit of food, and also create a sort of grinding motion. This makes the stomach an isolated chamber where the food that was chewed and swallowed in the mouth can be not only be stored for a short period of time, but also be mixed and ground to ensure that the chemicals released in the stomach are able to get to as many proteins as possible to start breaking them down.

So, although the stomach is certainly very important to start the digestive process for protein, when the food leaves the stomach and enters the small intestine, there is still quite a bit more digesting that needs to happen before our body can use the nutrients. Which means my early understanding of digestion was very inaccurate. 

Problems with Digestive Function

Although the stomach’s role in digestion might seem pretty straight forward, this is actually an area where things often go wrong. Sometimes the issue might be that we did not chew our food well enough and our stomach simply cannot make up for that. We might not be able to make enough stomach acid or enzymes to break down proteins because we don’t have enough nutrients available to make and release those chemicals into the stomach. When this happens, the food ends up staying in the stomach too long and it can get pretty putrid—yuck! Another possible problem is when the stomach cells struggle to make mucus and the digestive chemicals start to eat away at the cells and tissue that make up the stomach—ouch!

And problems in the stomach don’t just stay there. The esophagus does not have the same protective coating as the stomach, which is why it so important for that upper muscle to close tightly and keep any of the food in the stomach from going back into the esophagus. Even small amounts of weak acids can be pretty destructive and painful in the esophagus. 

And if food is not properly digested in the stomach, that is going cause problems later on in the intestines. This means you might experience issues like pain or bloating, and may not be getting all of the important nutrients from your food that your body needs to keep you healthy.