|  | Surgeries Operations | Surgeries

What Kind of Structure Is the Human Appendix?

The human appendix is a small structure located off the intestine. Herbivores, including rabbits, zebras and kangaroos, have appendixlike structures that are important for digesting plant material. However, the human appendix is considered a vestigial structure, meaning that it is an evolutionary remnant that does not perform any function vital to human life.

  1. Appendix Structure

    • The human appendix is a small, narrow offshoot of intestinal tissue located at the beginning of the large intestine. Its official name is the "vermiform appendix," which refers to its wormlike shape. The appendix can be 12 inches long in children, but it shrinks with age to reach a size of 2 to 8 inches in length and 0.28 to 0.31 inches in diameter. By middle age, the opening from the large intestine to the appendix has usually closed.

    Evolutionary History

    • Animals as diverse as the kangaroo have appendixlike structures.

      Human beings are not the only animals with an appendix. Many animals, including apes, zebras, rabbits and kangaroos, have intestinal offshoots that are similar in structure to the human appendix. In herbivores, these portions of the intestines are highly important for digestion. They contain bacteria necessary for the breakdown of cellulose, a hard-to-digest molecule found in plants. The location and structure of the human appendix is similar to these other animals, indicating that it was passed down through evolutionary history.

    Vestigial Structures

    • An ostrich's wings are vestigial structures.

      A vestigial structure is one that was passed down through evolutionary history but no longer performs its original function. One example of a vestigial structure is the wings of a flightless bird, such as an ostrich or emu. These species have wings because they are evolutionarily descended from birds that flew, but their wings no longer perform that function. The human appendix is also a vestigial structure, because it no longer has the ability to digest plant cellulose.

    Possible Functions

    • While the appendix is generally considered a vestigial structure, Williams and Myers argue in "Pathology of the Appendix" that the organ may have important immune functions. The appendix may produce immune cells that are used to fight disease and maintain levels of beneficial gut bacteria. However, removing the appendix generally causes no harm, indicating that its possible functions are not essential for human survival.

    Appendicitis

    • Surgical removal of the appendix usually results in no ill effects.

      In some situations the appendix can become inflamed, a condition called appendicitis. The symptoms of this condition are acute abdominal pain and tenderness in response to gentle pressure. Appendicitis occurs when the appendix is obstructed, causing infection and inflammation of the affected area. In serious cases, the appendix can burst and release bacteria that lead to further infection. The treatment for appendicitis is surgical removal, which usually results in no ill effects.

Surgeries - Related Articles