Anostril(ornaris/ˈnɛərɪs/,pl.:nares/ˈnɛəriːz/) is either of the twoorificesof thenose.They enable the entry and exit of air and other gasses through thenasal cavities.Inbirdsandmammals,they contain branched bones or cartilages calledturbinates,whose function is to warm air on inhalation and remove moisture on exhalation.Fishdo not breathe through noses, but they do have two small holes used forsmelling,which can also be referred to as nostrils (with the exception ofCyclostomi,which have just one nostril).
| Nostril | |
|---|---|
 Human nostrils | |
| Details | |
| Part of | Nose |
| System | Olfactory system |
| Identifiers | |
| Latin | naris |
| TA98 | A06.1.02.002 |
| TA2 | 3166 |
| Anatomical terminology | |
Inhumans,thenasal cycleis the normalultradian cycleof each nostril's blood vessels becoming engorged in swelling, then shrinking.
The nostrils are separated by theseptum.The septum can sometimes bedeviated,causing one nostril to appear larger than the other. With extreme damage to the septum and columella, the two nostrils are no longer separated and form a single larger external opening.
Like othertetrapods,humans have two external nostrils (anterior nares) and two additional nostrils at the back of the nasal cavity, inside the head (posterior nares, posterior nasal apertures orchoanae). They also connect the nose to the throat (the nasopharynx), aiding in respiration. Though all four nostrils were on the outside of the head of the aquatic ancestors of modern tetrapods, the nostrils for outgoing water (excurrent nostrils) migrated to the inside of the mouth, as evidenced by the discovery ofKenichthys campbelli,a 395-million-year-old fossilizedlobe-finned fishwhich shows this migration in progress. It has two nostrils between its front teeth, similar to humanembryosat an early stage. If these fail to join up, the result is acleft palate.[1]
Each external nostril contains approximately 1,000 strands ofnasal hair,which function to filter foreign particles such as pollen and dust.[2]
It is possible for humans to smell differentolfactoryinputs in the two nostrils and experience a perceptual rivalry akin to that ofbinocular rivalrywhen there are two different inputs to the two eyes.[3]Furthermore, scent information from the two nostrils leads to two types of neural activity[4]with the first cycle corresponding to the ipsilateral and the second cycle corresponding to the contralateral odor representations. In some cultures the extreme wide flaring of the nostrils accompanied by the baring of the upper teeth is often referred to as "doing the nostrils."
TheProcellariiformesare distinguished from other birds by having tubular extensions of their nostrils.
Widely-spaced nostrils, like those of thehammerhead shark,may be useful in determining the direction of an odour's source.[5][6]
See also
editReferences
edit- ^Lloyd, John;Mitchinson, John(2008).The Book of General Ignorance.London:Faber and Faber.pp. 2, 299.ISBN978-0-571-24139-2.OCLC191753333.Retrieved16 July2011.
- ^Blume-Peytavi, Ulrike; Whiting, David A.; Trüeb, Ralph M. (2008).Hair Growth and Disorders.Berlin: Springer. p. 10.ISBN978-3540469087.
- ^Zhou, Wen; Chen, Denise (29 September 2009)."Binaral rivalry between the nostrils and in the cortex".Current Biology.19(18):1561–5.Bibcode:2009CBio...19.1561Z.doi:10.1016/j.cub.2009.07.052.PMC2901510.PMID19699095.
- ^Dikeçligil, Gülce Nazlı; Yang, Andrew I.; Sanghani, Nisha; Lucas, Timothy; Chen, H. Isaac; Davis, Kathryn A.; Gottfried, Jay A. (November 2023)."Odor representations from the two nostrils are temporally segregated in human piriform cortex".Current Biology.33(24): 5275–5287.e5.Bibcode:2023CBio...33E5275D.doi:10.1016/j.cub.2023.10.021.PMC9948982.PMID36824705.
- ^Gardiner, Jayne M.; Atema, Jelle (July 2010)."The Function of Bilateral Odor Arrival Time Differences in Olfactory Orientation of Sharks".Current Biology.20(13):1187–1191.Bibcode:2010CBio...20.1187G.doi:10.1016/j.cub.2010.04.053.PMID20541411.S2CID13530789.
- ^"Cell Culture".Cell.142(4):501–503. August 2010.doi:10.1016/j.cell.2010.08.009.S2CID357010.
External links
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