The Appendix Protects Us From Germs And Protects Good Bacteria
You can read about this latest study in the Journal of Theoretical Biology.
After assessing several experiments and observations, the scientists believe that the good bacteria in the appendix that help our digestion can survive a bout of diarrhea that cleans out our gut, and appear to repopulate the gut.
The authors explained "While there is no smoking gun, the abundance of circumstantial evidence makes a strong case for the role of the appendix as a place where the good bacteria can live safe and undisturbed until they are needed."
The appendix is located near to where the large and small intestines meet; it is a slender pouch about two to four inches long. Its exact function has been a topic of debate by doctors - however, we have known that it contains immune system tissue.
Different microbes that help the digestive system break down foods inhabit the gut. The gut rewards these microbes by feeding them and keeping them safe. The scientists believe that the immune system cells located in the appendix have the function of protecting the good bacteria.
William Parker, Ph.D., and team have been observing the interplay of these bacteria in the intestines. They have documented the existence in the bowel of a biofilm - it is a thin and delicate layer of microbes, mucous and immune system molecules living together on the lining of the gut.
The authors explain "Our studies have indicated that the immune system protects and nourishes the colonies of microbes living in the biofilm. By protecting these good microbes, the harmful microbes have no place to locate. We have also shown that biofilms are most pronounced in the appendix and their prevalence decreases moving away from it."
Parker said "Diseases causing severe diarrhea are endemic in countries without modern health and sanitation practices, which often results in the entire contents of the bowels, including the biofilms, being flushed from the body." Because of the location of the appendix, it would be fairly difficult for anything to enter it as the bowels are emptied.
Parker adds "Once the bowel contents have left the body, the good bacteria hidden away in the appendix can emerge and repopulate the lining of the intestine before more harmful bacteria can take up residence. In industrialized societies with modern medical care and sanitation practices, the maintenance of a reserve of beneficial bacteria may not be necessary. This is consistent with the observation that removing the appendix in modern societies has no discernable negative effects."
Scientists had indicated many decades ago that people in industrialized nations may have a higher rate of appendicitis because of the "hygiene hypothesis", Parker commented. This hypothesis speculates that 'hygienic' societies have a higher incidence of autoimmune disease and allergy because their immune systems have not been challenged during everyday life by the ever so many parasites and other disease causing microbes found in normal environments. These hygienic society immune systems over-react when they are challenged.
Parker explained "This over-reactive immune system may lead to the inflammation associated with appendicitis and could lead to the obstruction of the intestines that causes acute appendicitis. Thus, our modern health care and sanitation practices may account not only for the lack of a need for an appendix in our society, but also for much of the problems caused by the appendix in our society."
As a direct examination of the function of the appendix would have been extremely difficult, Parker decided to carry out a deductive study. Rabbits, opossums and wombats are the only other animals, apart from humans, that are known to have appendices - their appendices are quite different from the human's.
"Biofilms in the large bowel suggest an apparent function of the human vermiform appendix"
Journal of Theoretical Biology
R. Randal Bollinger, Andrew S. Barbas, Errol L. Bush, Shu S. Lin and William Parker
Link to web page where a PDF can be downloaded (must be purchased)
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