copy 1 Flashcards
What are the two parts of the adrenal gland and where are they derived from?
Adrenal cortex (80-90%)– glandular tissue derived from embryonic mesoderm
Adrenal medulla (10-20%)– formed from neural ectoderm, can be considered a modified sympathetic ganglion
What is the function of the adrenal cortex and what are its three zones and what does each zone produce?
Synthesizes and releases steroid hormones (corticosteroids)
Zones:
Zona glomerulosa – mineralocorticoids (mainly aldosterone)
Zona fasciculata – glucocorticoids +Androgens (mainly cortisol and corticosterone)
Zona reticularis – gonadocorticoids + glucocorticoids (mainly dehydroepiandrosterone DHEA)
What is the first step in converting cholestrol to a steroid hormone and what enzyme catalyzes this step?
Conversion of Cholestrol to pregnenolone by dismolase
What are all the enzymes required to turn cholestrol to cortisol?
cholesterol desmolase, which converts cholesterol to
pregnenolone
17α-hydroxylase, which hydroxylates
pregnenolone to form 17-hydroxypregnenolone
3β-hydroxysteroid dehydrogenase, which converts 17-
hydroxypregnenolone to 17-hydroxyprogesterone;
21β-hydroxylase and 11β-hydroxylase, which
hydroxylate at C11 and C21 to produce the final
product, cortisol.
What happens if the 17a-hydroxylase step is blocked?
the zona fasciculata still can produce corticosterone without deleterious effect
What happens if there is a block at cholesterol desmolase, 3β -hydroxysteroid dehydrogenase, 21β -hydroxylase, or 11β -hydroxylase?
Blocks at the cholesterol desmolase, 3β -hydroxysteroid dehydrogenase, 21β -hydroxylase, or 11β -hydroxylase steps are devastating as they can prevent production of cortisol and corticosterone.
What are two examples of drugs that inhibit cortisol production and what is the mechanism behind them?
Example: Metyrapone and ketoconazole
Metyrapone: inhibits 11β -hydroxylase
Ketoconazole: inhibits several steps in the pathway including cholesterol desmolase, the first step.
