Appendix: Function of Appendix in Digestive System

By Shiwani PandeySeptember 14, 2022

Appendix - The Vestigial Organ

There are many organs or parts of organs in our body that do not function anymore. They are on the verge of obsolescence. We are also not sure what these organs actually did in the past. One such vestigial development is the appendix. It is a small pouch-like projection in the large intestinal region that might have had some functions but not now.


In this article, we will explore what the appendix is and what its probable functions.


What is Appendix?

An appendix is a small elongated sac or tube-like organ present at the beginning of the large intestine. Its location is very interesting. We can find an appendix in the right lower part of our abdomen close to the confluence of the small intestine and the large intestine. At this point, the small intestine ends and the large intestine begins.


The size of an appendix ranges between 3 and 4 inches. It means it is similar to the size of an adult’s smallest finger. To date, we are unable to figure out what functions this organ performed in the past. As of now, it is a vestigial organ and has no function whatsoever in the digestive system.


Probable Appendix Function

As discussed earlier, there is no such recorded physiological function of this organ. It remains located in the confluence of the intestines and has nothing to do with our digestive system. This question of appendix function has baffled physiologists and researchers for centuries. What is the purpose of this organ? Is it just an extrapolation of the intestines? If it is a vestigial organ, then what was its function?


It is still unclear what this mystery organ does or did. It lies like a small tube and often causes a nuisance by being inflamed or infected. This organ, as said before, has no direct or indirect role in the digestive system of a human being. Even if it is operated on and removed, we will not face any digestive or other physiological issues without it.


Theories behind Appendix

Now that we are familiar with the function of the appendix in the digestive system, let us know about the several theories put forward by scientists and researchers about the origin and function of the appendix. 


As per the scientists, this organ has been inherited from our ancestors and has undergone several changes over the years in its shape. This is just an evolutionary phase of this organ where it has got smaller. Thousands of years back, it might have had any function that contributed to our digestive system.


Charles Darwin, the father of evolution, referred to this organ and marked it as an evolutionary residual of the human digestive system. He suggested that this organ might have been a part of a large cecum, the first part of our large intestine.


According to Darwin, this enlarged appendix used to be another part of our large intestine when we were herbivores. This organ might have been used as temporary storage of plants. It might also be the residence of friendly bacteria that helped humans to digest such plant tissues easily.


Due to evolution, our ancestors shifted from a plant-based diet to a fruit-based diet. Fruits are comparatively easier to digest than leaves. Consequently, this organ might have started to lose its function in due course of time. The use of appendix became minimal when we shifted to an omnivorous diet and started to eat cooked food.


This can be the possible reason behind the obsolescence of the function of the appendix. We don’t even have a big cecum. Moreover, we have lost the function of the appendix when we start to eat cooked food. Darwin concluded that the appendix was a pouch-shaped organ located right beneath the cecum and might have been the habitat of friendly bacteria used for plant tissue digestion.


On the contrary, Randy Bollinger and William Parker, Duke University Medical Center, proposed that it is the home to gut bacteria. Appendices can be found in many animals and their function can be deducted from them. Despite their speculations, there is no solid evidence.


On careful analysis, they concluded that the appendix is the hub of gut bacteria. All the friendly bacterial species stay there until an infection breaks out causing appendicitis. Removing this organ will not cause any harm.


The Location of Appendix


The Location of Appendix


Cause of Appendicitis

If you see the image of the appendix, you will find out where it is located. This organ is not in use anymore and can cause infection. As mentioned earlier, it is the hub where gut bacteria lie. This pouch increases in size when there is an uncontrolled growth of bacteria infecting the tissues. It causes the appendix burst and serious complications can occur.


The doctors then perform an invasive surgery called appendectomy where this organ is removed from the digestive system safely. The treatment of the infection is done using antibiotics.


Appendix: Do We Need It?

As per this discussion, we can conclude that the historic physiological function of the appendix is still not known. We also don’t know what it does but it does not cause any harm when removed from the digestive system.


Its consequence-free removal suggests that there is no function of the appendix as such in the digestive system. According to Darwin and modern researchers, it can be the hub of gut bacteria. Its infection causes severe pain and needs its safe removal from the system through an appendectomy.