GI Tract: Function

Mar 5, 2017 by


You can have me read this article to you instead of reading it yourself…

Or you can read it the old-fashioned way below…

Getting a basic grip on the GI tract requires an understanding of four main concepts.  The first of those is function.

Knowing how the GI tract is supposed to function allows us to understand what goes wrong when those functions break.  And understanding what goes wrong when something breaks gives us some guidance on how to go about fixing it.

The function of the GI tract is only one piece of the puzzle, though.  And it’s hard to fully understand it without also covering the structure of our GI system.  This section will provide a basic overview, and then we will discuss the structure of the GI system in the following article.

So let’s do this!


The GI tract is primarily known for its role in digestion. For our purposes, there are two main types of digestion that occur in the GI tract: mechanical and chemical.

Mechanical implies physical impact on the food/substances that are passing through the GI tract. This can be in the form of chewing and also in the form of the stomach grinding down its contents.

Chemical implies that some type of substance in the body is breaking down the food at the molecular level.  This happens in multiple parts of the GI tract with various types of fluids, such as stomach acid.


The whole purpose of taking in food (besides the fact that it tastes good!) is to provide our bodies with nutrition.  That means that a primary role of the GI tract is to absorb the nutrients that are found in the foods that we eat.

Absorption occurs in various parts of the GI tract, but can only be completed once digestion has taken place and broken the food down into smaller components. Our bodies have developed a variety of interesting and creative ways of accessing the nutrients that we consume.


The GI tract is also quite well known for its role in ridding our bodies of waste in the form of stool.  Many actions occur that lead to the proper formation of stool that is not too hard and not too soft.  This all happens after, hopefully, the nutrients and water in the food that was consumed have been properly absorbed by the body.

Other Functions

As the GI tract has become the subject of renewed research and interest, we are constantly discovering new functions that we didn’t know existed.  And we are also beginning to realize that the GI tract is much more complex than was ever thought to be possible.

It has now become clear that the GI tract is actually the largest component of the body’s immune system. It also seems that the human GI tract plays an important role in the endocrine (hormone) system. These findings are just the beginning of an evolving field of science that will probably lead to a large shift in the way that we view our GI tracts.

Depending on your GI diagnosis, these findings may or may not change your perspective or management over time.  But we will be certain to cover them here at Your GI Journey!  In the meantime, we will place more focus on the 3 main functions that we already discussed: digestion, absorption, and excretion.

Next: GI Tract Structure

Or refer back to the GI Tract Info Hub.

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