This article is an excerpt from the Shortform book guide to "Gut" by Giulia Enders. Shortform has the world's best summaries and analyses of books you should be reading.
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Is the appendix useless? What is the purpose of the appendix?
The appendix has a reputation of having no practical purpose in the body, but that’s not true. The appendix is a vital part of the digestive system; it kills bad bacteria and maintains good bacteria.
Learn why the appendix isn’t so useless after all, according to scientist Giulia Enders.
The Large Intestine and Appendix
Is the appendix a useless organ?
To understand the purpose of the appendix, we have to look at the large intestine because the appendix is attached to it. Enders notes that the small intestine is remarkably efficient at absorbing food particles. However, it can’t process everything. This is where the large intestine comes in: Helped by a huge population of bacteria, its job is to digest nutrients that the small intestine can’t absorb.
Attached to the large intestine is the appendix. Despite its reputation as a useless organ, Enders argues that the appendix helps digestion by maintaining the gut’s population of healthy bacteria.
Let’s take a closer look at the role of each organ.
The Large Intestine
According to Enders, the large intestine is in charge of breaking down and absorbing nutrients and water left over by the small intestine. It slowly absorbs water and electrolytes from the chyme, ensuring that we don’t lose too many fluids when we poop.
Enders explains that the large intestine houses the vast majority of the bacteria in your gut. These bacteria use enzymes to squeeze the last nutrients out of the chyme. The walls of the large intestine then absorb the nutrients into the bloodstream.
(Shortform note: The large intestine absorbs water through osmosis. Osmosis is a process in which water moves across a semi-porous membrane—a barrier that only allows certain particles through. In the large intestine, water moves from inside the gut, through the gut wall membrane, and into the bloodstream. Once osmosis is complete and the chyme is dehydrated, the large intestine produces mucus to help keep it moving and bind it together into poop.)
Is the Appendix Useless?
The appendix attaches to the large intestine on the lower right side of your abdomen. Enders maintains that, contrary to popular belief, the appendix isn’t useless. According to Enders, the appendix consists of the same tissue that makes up your tonsils. Researchers theorize that, like the tonsils, the appendix captures and kills bad bacteria.
Researchers also suggest that the appendix repopulates our large intestine with helpful bacteria. When we have diarrhea, we poop out a lot of our gut bacteria. To compensate, Enders explains, the appendix releases helpful bacteria into the large intestine. This restores a healthy balance and prevents harmful invaders from settling in the gut.
(Shortform note: Recent research has supported Enders’s claims and extended scientists’ understanding of the appendix. A 2017 study analyzed over 500 mammal species and found that species with appendices had more immune tissue than those without them. This supports the theory that the appendix captures and kills bad bacteria. Furthermore, a 2018 study suggested that the appendix both creates an immune response and serves as a repository for good bacteria, backing up Enders’s claims.)
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Like what you just read? Read the rest of the world's best book summary and analysis of Giulia Enders's "Gut" at Shortform .
Here's what you'll find in our full Gut summary :
- How your digestive system works and why it’s important to keep it healthy
- How tiny organisms in your intestines influence your immune system (and possibly your mood)
- What your appendix actually does
