Ganong's Physiology Examination and Board Review by Kim E. Barrett Susan M. Barman Scott Boitano jane f. reckelhoff

Author:Kim E. Barrett, Susan M. Barman, Scott Boitano, jane f. reckelhoff
Language: eng
Format: epub
Published: 2018-07-03T16:00:00+00:00

ADRENAL CORTEX: STRUCTURE & BIOSYNTHESIS OF ADRENOCORTICAL HORMONES

CLASSIFICATION & STRUCTURE

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The hormones of the adrenal cortex are derivatives of cholesterol and contain the cyclopentanoperhydrophenanthrene nucleus. Gonadal and adrenocortical steroids are of three types: C 21 steroids, which have a two-carbon side chain at position 17; C 19 steroids, which have a keto or hydroxyl group at position 17; and C 18 steroids, which, in addition to a 17-keto or hydroxyl group, have no angular methyl group attached to position 10. The adrenal cortex secretes primarily C 21 and C 19 steroids. Most of the C 19 steroids have a keto group at position 17 and are therefore called 17-ketosteroids. The C 21 steroids that have a hydroxyl group at the 17 position in addition to the side chain are often called 17-hydroxycorticoids or 17-hydroxycorticosteroids.

The C 19 steroids have androgenic activity. The C 21 steroids are classified as mineralocorticoids or glucocorticoids. All secreted C 21 steroids have both mineralocorticoid and glucocorticoid activity; mineralocorticoids are those in which effects on Na + and K + excretion predominate and glucocorticoids are those in which effects on glucose and protein metabolism predominate.

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