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The steroid hormones are all derived from cholesterol. Moreover, with the exception of vitamin D, they all contain the same cyclopentanophenanthrene ring and atomic numbering system as cholesterol. The conversion of C27 cholesterol to the 18-, 19-, and 21-carbon steroid hormones (designated by the nomenclature C with a subscript number indicating the number of carbon atoms, e.g. C19 for androstanes) involves the rate-limiting, irreversible cleavage of a 6-carbon residue from cholesterol, producing pregnenolone (C21) plus isocaproaldehyde. Common names of the steroid hormones are widely recognized, but systematic nomenclature is gaining acceptance and familiarity with both nomenclatures is increasingly important. Steroids with 21 carbon atoms are known systematically as pregnanes, whereas those containing 19 and 18 carbon atoms are known as androstanes and estranes, respectively. The important mammalian steroid hormones are shown below along with the structure of the precursor, pregneolone. Retinoic acid and vitamin D are not derived from pregnenolone, but from vitamin A and cholesterol respectively.

Pregnenolone: produced directly from cholesterol, the precusor molecule for all C18, C19 and C21 steroids Progesterone: a progestin, produced directly from pregnenolone and secreted from the corpus luteum, responsible for changes associated with luteral phase of the menstrual cycle, differentiation factor for mammary glands Aldosterone: the principal mineralocorticoid, produced from progesterone in the zona glomerulosa of adrenal cortex, raises blood pressure and fluid volume, increases Na+ uptake Testosterone: an androgen, male sex hormone synthesized in the testes, responsible for secondary male sex characteristics, produced from progesterone Estradiol: an estrogen, principal female sex hormone, produced in the ovary, responsible for secondary female sex characteristics Cortisol: dominant glucocorticoid in humans, synthesized from progesterone in the zona fasciculata of the adrenal cortex, involved in stress adaptation, elevates blood pressure and Na+ uptake, numerous effects on the immune system

All the steroid hormones exert their action by passing through the plasma membrane and binding to intracellular receptors. The mechanism of action of the thyroid hormones is similar; they interact with intracellular receptors. Both the steroid and thyroid hormone-receptor complexes exert their action by binding to specific nucleotide sequences in the DNA of responsive genes. These DNA sequences are identified as hormone response elements, HREs. The interaction of steroid-receptor complexes with DNA leads to altered rates of transcription of the associated genes.

Pregnenolone: produced directly from cholesterol, the precusor molecule for all C18, C19 and C21 steroidsProgesterone: a progestin, produced directly from pregnenolone and secreted from the corpus luteum, responsible for changes associated with luteral phase of the menstrual cycle, differentiation factor for mammary glandsAldosterone: the principal mineralocorticoid, produced from progesterone in the zona glomerulosa of adrenal cortex, raises blood pressure and fluid volume, increases Na+ uptakeTestosterone: an androgen, male sex hormone synthesized in the testes, responsible for secondary male sex characteristics, produced from progesteroneEstradiol: an estrogen, principal female sex hormone, produced in the ovary, responsible for secondary female sex characteristicsCortisol: dominant glucocorticoid in humans, synthesized from progesterone in the zona fasciculata of the adrenal cortex, involved in stress adaptation, elevates blood pressure and Na+ uptake, numerous effects on the immune system
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8y ago
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13y ago

Examples of steroids are Methyltestosterone and Pregnonolone. Synthetic anabolic steroids are chemically different from the testosterone made by the body. They do not accomplish the same medical effects for you that natural testosterones do. Instead, they have been proven to cause dangerous side effects that can cause serious health issues and even death.

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11y ago

cholesterol and estrogen

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11y ago

Cholesterol and Estrogen (estrogen is a hormone found in women and producing too much of it is not good for your health).

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13y ago

Hydrocortisone, betamethasone, etc

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6y ago

Prednisone is one example of a steroid.

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Q: What is an example of a steroid hormone?
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