Chapter 9 - 3

03 Medicine

The Function of the Appendix

The appendix is a small organ shaped like a pouch located along the intestinal tract of the human body. Since its discovery, physicians have been unable to reach a consensus regarding its purpose.

They have, however, been able to confirm that the inside of the appendix is lined with tissue called biofilm, designed to kill harmful bacteria.

Although there are a number of harmful bacteria that can enter the intestinal tract, the contents of the digestive tract do not enter the appendix, nor is the appendix known to secrete anything into the intestine. Thus, it was unclear how this immune tissue was used.

Given the lack of an apparent purpose for the appendix, many physicians went so far as to suggest that it served no purpose whatsoever. However, recent studies have shed some light on the possible uses of the appendix.

Researchers from Duke University began their study by examining the inner wall of the appendix coated in a thin biofilm. They found that the biofilm is a mixture of mucus, bacterial colonies, and immune system molecules. These immune molecules in the biofilm protect helpful bacteria colonies. Meanwhile, the biofilm extends outward into the actual intestinal tract where the appendix connects.

Because of protection the biofilm offers to helpful bacteria that inhabit the intestine, researchers suspect that the appendix is used to house this bacteria and to keep a “reserve” of them on hand.

With this hypothesis, scientists began conducting research into the contents of patients’ intestinal tracts. Normally, helpful bacteria exist within the intestinal tract to aid in the digestive process.

The digestive tract houses these helpful bacteria, and the immune molecules keep harmful bacteria from entering. However, the immune molecules cannot always keep out the harmful bacteria.

When they do enter, they can cause ailments such as diarrhea. When a person has diarrhea, the contents of the intestinal tract, including the helpful bacteria, are entirely flushed out. Researchers found that patients’ intestinal tracts were quickly repopulated with good bacteria shortly after they were emptied.

This observation reinforces the hypothesis that the appendix acts as a reserve for good bacteria. After the intestinal tract was emptied, the appendix could release a portion of the good bacteria back into, the gut.

Other observations support this hypothesis. In third-world countries where harmful intestinal viruses are common, it is possible that the biofilm coating the appendix and a part of the intestine are flushed out. The theory also helps explain why removal of the appendix—a common procedure in developed countries − has no discernable effect on a person. Since the reserves of helpful bacteria are not needed, their absence has no negative impact on people without appendixes in civilized countries.

This hypothesis remains untested, however. It is difficult for doctors to actively monitor the intestinal activity so closely in a normal human being. Furthermore, accurate tests cannot be performed in other animals.

Only rabbits, possums, and wombats are known to have appendixes.

Furthermore, their appendixes are markedly different from their human counterparts. As such, science cannot be sure of the precise function of the appendix.