|MadSci Network: Anatomy|
What was the appendix used for?
By appendix I assume you mean the vermiform appendix, which is a worm-like appendage that projects off the cecum and is found in the lower right quadrant of the abdomen. Many people claim that the vermiform appendix is a vestigial organ (an organ that is a holdover from our evolutionary ancestry, but which no longer serves any important function). That claim, however, has little scientific support. Therefore, the real question should be: What is the appendix used for?
A vermiform appendix (of some type or other) can be found in nearly every mammal. This suggests that the appendix is important to mammalian physiology. Further evidence of the importance of this organ is found in the fact that it has its own blood supply, and an independent mesentery (this indicates that the appendix is not a "part" of some other organ). That said, however, the actual function of the appendix remains a mystery. According to Romer and Parsons (The Vertebrate Body 1977 p. 354) "Its major importance would appear to be financial support of the surgical profession." This is a rather cynical view, but it does emphasize the fact that we can live just fine without our appendix.
Current theory points to the fact that the vermiform appendix contains a great deal of lymphatic channels. Lymph is the body's primary method for combating infection and foreign bacteria. The appendix also happens to feed into the cecum at the beginning of the large intestine. The large intestine is the home to many types of bacteria (e. coli being the most common). These bacteria are not all "bad" and may play an important role in our digestion processes. However, bacteria populations can get out of control sometimes, and that's when the lymphatics of the appendix may be important. In effect, the appendix may help to regulate the population of bacteria in our gut.
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