Blackhead

Blackhead
A familiar term for what is medically called an open comedo. A comedo, the primary sign of acne, consists of a dilated (widened) hair follicle filled with keratin squamae (skin debris), bacteria, and sebum (oil). An open comedo has a wide opening to the skin and is capped with a blackened mass of skin debris. By contrast, a closed comedo has an obstructed opening to the skin and may rupture to cause a low-grade skin inflammatory reaction in the area. The common name for a closed comedo is a whitehead. Acne occurs when sebaceous glands of the skin begin to secrete oil during puberty. These glands are stimulated by male hormones that are produced in the adrenal glands of both boys and girls. The oil lubricates and protects the skin. Under certain circumstances, cells that are close to the openings of the sebaceous glands block the openings. This causes a buildup of oil underneath the skin. Bacteria, which live in everyone's skin but generally mind their own business, feast on this oil, multiply, and cause the surrounding tissues to become inflamed. If the inflammation is right near the surface, a pustule is formed; if it is deeper, a papule (pimple); deeper still and it becomes a cyst. If the oil breaks though to the surface, the result is a whitehead. If the oil becomes oxidized (that is, acted on by oxygen in the air), the oil changes from white to black, and the result is a blackhead. This is how the two types of comedones develop.

* * *

black·head 'blak-.hed n
1) a small plug of sebum blocking the duct of a sebaceous gland esp. on the face compare MILIUM
2) a destructive disease of turkeys and related birds caused by a protozoan of the genus Histomonas (H. meleagridis) that invades the intestinal ceca and liver called also enterohepatitis, histomoniasis, infectious enterohepatitis

* * *

n.
a plug formed of fatty material (sebum and keratin) in the outlet of a sebaceous gland in the skin; the black colour is due to melanin. See also acne. Medical name: comedo.

* * *

black·head (blakґhed) 1. open comedo. 2. histomoniasis.

Medical dictionary. 2011.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Blackhead — bezeichnet Blackhead Range, einen Gebirgszug in den nördlichen Catskills von New York, USA. Blackhead Mountain, einen Berggipfel in der Blackhead Range Blackhead Point, auch Tai Pau Mai, ein Kap in Hong Kong. Blackhead (Kanada) in Kanada… …   Deutsch Wikipedia

  • Blackhead — Black head , n. (Zo[ o]l.) The scaup duck. [1913 Webster] …   The Collaborative International Dictionary of English

  • Blackhead —   [ blækhed, englisch], Tiermedizin: Typhlohepatitis …   Universal-Lexikon

  • blackhead — comedo, 1837, from BLACK (Cf. black) (adj.) + HEAD (Cf. head) (n.). So called for its appearance …   Etymology dictionary

  • blackhead — ► NOUN ▪ a plug of oily matter in a hair follicle …   English terms dictionary

  • blackhead — [blak′hed΄] n. 1. any of various black headed birds, esp. the scaup duck 2. a black tipped plug of dried fatty matter in a pore of the skin ☆ 3. an infectious disease of the intestines and liver of turkeys, chickens, etc. caused by a protozoan… …   English World dictionary

  • Blackhead — This article is about the skin condition. For other uses, see Blackhead (disambiguation). Blackhead Classification and external resources Blackheads on a nose. ICD 9 …   Wikipedia

  • blackhead — UK [ˈblækˌhed] / US noun [countable] Word forms blackhead : singular blackhead plural blackheads a small black spot on your skin, caused by dirt or oil blocking a pore (= one of the small holes in your skin) …   English dictionary

  • blackhead — Scaup Scaup (sk[add]p), n. [See {Scalp} a bed of oysters or mussels.] 1. A bed or stratum of shellfish; scalp. [Scot.] [1913 Webster] 2. (Zo[ o]l.) A scaup duck. See below. [1913 Webster] {Scaup duck} (Zo[ o]l.), any one of several species of… …   The Collaborative International Dictionary of English

  • blackhead — Broadbill Broad bill , n. 1. (Zo[ o]l.) A wild duck ({Aythya marila}, or {Fuligula marila}), which appears in large numbers on the eastern coast of the United States, in autumn; called also {bluebill}, {blackhead}, {raft duck}, and {scaup duck}.… …   The Collaborative International Dictionary of English

  • blackhead — /blak hed /, n. 1. a small, black tipped, fatty mass in a skin follicle, esp. of the face; comedo. 2. any of several birds having a black head, as the greater scaup, Aythya marila. 3. Also called enterohepatitis. Vet. Pathol. a malignant,… …   Universalium

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”