• Question: why do have an appendix?

    Asked by cliodhna27 to Enda, Jean, Kate, Kev, Tim on 16 Nov 2012.
    • Photo: Jean Bourke

      Jean Bourke answered on 16 Nov 2012:

      In herbivores (animals that just eat plants) the appendix is know as the cecum and in significantly larger than in humans. The cecum is full of friendly bacteria that help these animals digest the fibre in their food.

      Our dies are relatively low in the tough to digest cellulose so we don’t need it to do this. Technically it is vestigial as it no longer does what it used to, that’s not to say it has no use! There are various theories about what the appendix does in humans and come applications.

      When you’re really sick and have diarrhea or something like that your gut bacteria can be significantly depleted the appendix can help some of your necessary gut bacteria survive. The bacteria that have managed to shelter in the appendix can then help recolonize your gut restoring your nice healthy gut flora.

      The human appendix as been found to lot of immune cells and so it could be important
      he appendix is experimentally verified as being rich in infection-fighting lymphoid cells, so it could be important for keeping you healthy.

      It has a few uses in medicine: it can be used as a way into a blocked gut allowing the gut to be “cleaned”

      The appendix can also be used to reconstruct damaged or diseased bit of the body, such as the bladder. If you use a bit of your own body you avoid any problems trying to find a donor and you don’t reject your own tissue!

      So the appendix can be very useful indeed.

    • Photo: Enda O'Connell

      Enda O'Connell answered on 16 Nov 2012:

      Hi Cliodhna,

      Great question. In humans, the appendix is called a “vestigial” structure, which means it has lost most of its function as we have evolved. Earlier in our development, the appendix was the caecum, which would have helped us break down the cellulose in plants. The caecum is particularly important in herbivores like horses or koalas, who live almost entirely on eucalyptus leaves, which are toxic to most other animals.

      As our ancestors evolved, their diet started to include more food that was easier to break down, so they didn’t need the caecum as much. This continued and the caecum began to shrink into what is known as the appendix today. Other examples of vestigial structures in humans include your tailbone or “coccyx” at the end of your spine and your wisdom teeth.

      There is some evidence that it continues to be useful in the body, as a home for useful bacteria that help in digestion, particularly when we get sick and our other bacteria are flushed from our system, acting as a kind of “safe house” from where our “good bacteria” can be replenished.

      The appendix often needs to be removed due to appendicitis or sometimes cancer. Appendicitis occurs when a blockage causes a build up of mucus, followed by swelling and pain. This nearly always requires your appendix to be removed as if it is left untreated, it can burst causing blood poisoning (septicaemia). Removal of an appendix is a routine surgery and it only takes a couple of weeks to make a full recovery.

      Do you still have your appendix?