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Appendicitis is inflammation of the appendix, a small, potentially vestigial organ that branches off the large intestine. Inflammation is usually a result of some sort of obstruction in the lumen of the appendix, which ultimately leads to infection.
Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function.. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
Appendicitis is one of the most frequent diagnoses for emergency department visits resulting in hospitalization among children ages 5–17 years in the United States. [108] Adults presenting to the emergency department with a known family history of appendicitis are more likely to have this disease than those without. [109]
The human appendix is a vestigial organ thought to serve no purpose. Appendicitis, an infection of this organ, is a certain death without medical intervention. "During the past few years, however, several studies have suggested its immunological importance for the development and preservation of the intestinal immune system."
A Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the vitelline duct.It is the most common malformation of the gastrointestinal tract and is present in approximately 2% of the population, [1] with males more frequently experiencing symptoms.
It is also called appendicolith when it occurs in the appendix and is sometimes concurrent with appendicitis. [1] They can also obstruct diverticula. It can form secondary to fecal impaction. A fecaloma is a more severe form of fecal impaction, and a hardened fecaloma may be considered a giant fecalith. The term is from the Greek líthos=stone. [2]
If a structure was once called vestigial, but is now known to be functional, then calling it "Functioning Vestigial Structures" violates the definition of vestigial, because by definition, it is not vestigial. It was previously called vestigial, but that was a mistake. It is not correct to call the vermiform appendix vestigial.