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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]
This definition is consistent with Wiedersheim, who said that vestigial organs are "wholly or in part functionless" (Wiedersheim 1893, p. 200) and have "lost their original physiological significance" (p. 205). Although Wiedersheim's originally published list contains 86 items, later interpretations enlarged his list to 180 vestiges.
Vestigial structures are anatomical structures of organisms in a species which are considered to have lost much or all of their original function through evolution. [8] These body parts can be classed as additional to the required functioning of the body. In human anatomy, the vermiform appendix is sometimes classed as a vestigial remnant.
The mucosa-associated lymphoid tissue (MALT), also called mucosa-associated lymphatic tissue, is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body, such as the gastrointestinal tract, nasopharynx, thyroid, breast, lung, salivary glands, eye, and skin.
Cotard's syndrome withdraws the person with the condition from other people due to neglect of their personal hygiene and physical health. Delusions of negation of self prevent the patient from making sense of external reality, which then produces a distorted view of the external world. Such delusions of negation are usually found in ...
According to the Cleveland Clinic, this rare cancer spreads by secreting mucin, a component of mucus, inside a person's abdomen, causing it to fill up with a jelly-like substance.
The formation of goose bumps in humans under stress is considered by some to be a vestigial reflex, [4] though visible piloerection is associated with changes in skin temperature in humans. [5] The reflex of producing goose bumps is known as piloerection or the pilomotor reflex , or, more traditionally, [ 6 ] horripilation .