Ušesno maslo

Ušesno maslo, ušesna smola ali cerumen je rjavkast voskast izloček žlez mastilk (cerumenskih žlez) v sluhovodu, ki vsebuje tudi izloček lojnic in odluščene celice povrhnjice.[1] V sluhovodu nastaja pri človeku in drugih sesalcih. Ščiti kožo zunanjega sluhovoda, omogoča njegovo čiščenje in mazanje, hrati pa deloma ščiti pred vdorom bakterij, gliv, žuželk in vode.[2]

Sestava

Glavna sestavina ušesnega masla so odluščene celice kože. Okoli 60 % predstavlja keratin, 12–20 % nasičene in nenasičene dolgoverižne maščobne kisline prisotni so še alkoholi, skvaleni in 6–9 % holesterola.[3]

Vlažna in suha oblika

Obstajata dve genetsko pogojeni vrsti ušesnega masla: vlažno ušesno maslo, ki je genetsko dominantno, in suho ušesno maslo, ki je recesivno. Suho ušesno maslo je sivo in drobljivo ter je bolj značilno za Azijce in ameriške domorodce, medtem ko je vlažno ušesno maslo mokro, medenorjave do temnorjave barve in bolj značilno za črnce in Evropejce.[4] S pomočjo preučevanja vrste ušesnega masla so antropologi ugotavljali selitvene vzorce ljudstev v preteklosti, na primer Inuitov.[5] Razlika v obeh vrstah je posledica sestave; vlažno ušesno maslo vsebuje več lipidov (50 %) in pigmentnih zrnc kot suho ušesno maslo (suho ušesno maslo vsebuje okoli 30 % lipidov).[3] Genetsko je vzrok v spremembi enega baznega para (polimorfizem posameznega nukleotida) v genu ABCC11.[6] Posamezniki s suhim ušesnim maslom so homozigoti za adenin, medtem ko imajo posamezniki z vlažnim ušesnim maslom na tem mestu v genu vsaj en gvanin.[7]

Prekomerno nastajanje

Prekomerno nastajanje ušesnega masla lahko moti prehod zvoka po sluhovodu in povzroči prevodno naglušnost.[8]

Sklici

  1. ↑ http://lsm1.amebis.si/lsmeds/novPogoj.aspx?pPogoj=cerumen[mrtva povezava], Slovenski medicinski e-slovar, vpogled: 11. 6. 2013.
  2. ↑ Earwax Arhivirano 2009-02-25 na Wayback Machine. at the American Hearing Research Foundation. Chicago, Illinois 2008.
  3. ↑ 3,0 3,1 Guest JF; Greener MJ; Robinson AC; Smith AF (Avgust 2004). »Impacted cerumen: composition, production, epidemiology and management«. QJM. 97 (8): 477–88. doi:10.1093/qjmed/hch082. PMID 15256605.
  4. ↑ Overfield, Theresa (1985). Biologic variation in health and illness: race, age, and sex differences. Menlo Park, Calif: Addison-Wesley, Nursing Division. str. 46. ISBN 0-201-12810-1. ... most common type in Whites and Blacks is dark brown and moist. Dry wax, most common in Orientals and Native Americans, is gray and dry. It is flaky and may form a thin mass that lies in the ear canal.
  5. ↑ Bass EJ; Jackson JF (september 1977). »Cerumen types in Eskimos«. American Journal of Physical Anthropology. 47 (2): 209–10. doi:10.1002/ajpa.1330470203. PMID 910884.{{navedi časopis}}: Vzdrževanje CS1: samodejni prevod datuma (povezava)
  6. ↑ Online 'Mendelian Inheritance in Man' (OMIM) 117800
  7. ↑ Yoshiura K; Kinoshita A; Ishida T; in sod. (Marec 2006). »A SNP in the ABCC11 gene is the determinant of human earwax type«. Nature Genetics. 38 (3): 324–330. doi:10.1038/ng1733. PMID 16444273.
  8. ↑ Oliveira RJ (1997). »The active earcanal«. Journal of the American Academy of Audiology. 8 (6): 401–410. PMID 9433686.

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