AskDefine | Define steroid

Dictionary Definition

steroid

Noun

1 any of several fat-soluble organic compounds having as a basis 17 carbon atoms in four rings; many have important physiological effects
2 any hormone affecting the development and growth of sex organs [syn: steroid hormone, sex hormone]

User Contributed Dictionary

English

Etymology

From sterol + -oid.

Pronunciation

  • /ˈstɛrɔɪd/

Noun

  1. A class of organic compounds having a structure of 17 carbon atoms arranged in four rings; they are lipids, and occur naturally as sterols, bile acids, adrenal and sex hormones, and some vitamins; many drugs are synthetic steroids.
  2. Any anabolic hormone used to promote muscle growth.
  3. sports US Any chemical compound used to enhance athletic performance.

Translations

class of organic compounds

Extensive Definition

A steroid is a terpenoid lipid characterized by a carbon skeleton with four fused rings, generally arranged in a 6-6-6-5 fashion.
Steroids vary by the functional groups attached to these rings and the oxidation state of the rings. Hundreds of distinct steroids are found in plants, animals, and fungi. All steroids are made in cells either from the sterol lanosterol (animals and fungi) or the sterol cycloartenol (plants). Both sterols are derived from the cyclization of the triterpene squalene.

Origin

Steroids include estrogen (US spelling) or oestrogen (UK/AUS spelling), progesterone and testosterone. Estrogen and progesterone are made primarily in the ovary and in the placenta during pregnancy and testosterone in the testes. Testosterone is also converted into estrogen to regulate the supply of each, in the bodies of both females and males. Certain neurons and glia in the central nervous system (CNS) express the enzymes that are required for the local synthesis of pregnane neurosteroids, either de novo or from peripherally derived sources. The rate limiting step of steroid synthesis is the conversion of cholesterol to pregnenolone which occurs inside the mitochondrion.

Classification

Taxonomical/Functional

Some of the common categories of steroids:

Structural

It is also possible to classify steroids based upon their chemical composition. One example of how MeSH performs this classification is available at the Wikipedia MeSH catalog. Examples from this classification include:

External links

steroid in Arabic: ستيرويد
steroid in Bulgarian: Стероид
steroid in Catalan: Esteroide
steroid in Czech: Steroidy
steroid in German: Steroide
steroid in Spanish: Esteroide
steroid in Esperanto: Steroido
steroid in French: Stéroïde
steroid in Korean: 스테로이드
steroid in Croatian: Steroidi
steroid in Italian: Steroide
steroid in Hebrew: סטרואיד
steroid in Malay (macrolanguage): Steroid
steroid in Dutch: Steroïde
steroid in Japanese: ステロイド
steroid in Norwegian: Steroid
steroid in Occitan (post 1500): Esteroïd
steroid in Polish: Steroidy
steroid in Portuguese: Esteróide
steroid in Romanian: Steroid
steroid in Russian: Стероиды
steroid in Simple English: Steroid
steroid in Slovak: Steroid
steroid in Serbian: Стероиди
steroid in Serbo-Croatian: Steroidi
steroid in Finnish: Steroidi
steroid in Swedish: Steroid
steroid in Thai: สเตอรอยด์
steroid in Turkish: Steroid
steroid in Chinese: 類固醇
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