Adrenalcorticoids Summary Flashcards
How are adrenal steroids synthesized?
By enzymatic modification of cholesterol (like all steroid hormones)
Where does cholesterol come from for steroidogeneisis?
Acquired from dietary sources or synthesized in liver. De novo synthesis also possible.
What is the primary glucocorticoid? What does it have negative feedback control of?
Cortisol. Hypothalamic (CRF) and anterior pituitary hormone (POMC/ACTH) release.
What regulates glucocorticoid production?
ACTH. Side chain cleavage enzyme is under ACTH regulation making the production of pregnenolone the rate limiting step.
What enzyme is responsible for progesterone conversion to glucocorticoids?
21 hydroxylase.
What happens if 21 hydroxylase is defective?
There is a lack of glucocorticoids AND mineralocorticoids and an excess of androgens. Hypotension is seen with this. It is the most common genetic defect.
What is the function of 11B-hydroxylase (11 B hydroxysteroid dehydrogenase)?
It converts deoxycorticosteroids to glucocorticoids and mineralcorticoids.
What happens when 11B hydroxylase is defective?
There is a lack of cortisol and aldosterone. However, deoxycorticosterone and 11 deoxycortisol are made which have weak mineralocorticoid activity. HTN seen with 11B-hydroxylase defects.
What does Aldosterone regulate?
Sodium and K balance
How does Aldosterone influence ACTH?
Has no effect on ACTH.
What is hypercortisolism (cushing syndrome) usually due to?
Cushing disease
What is hypocortisolism (adrenal insufficiency) usually due to?
Addison’s disease or congenital adrenal hyperplasia.
What is co-incident with production of high levels of POMC (ACTH and MSH)?
Hyperpigmentation
What stimulates melanocyte production of melanin?
ACTH and MSH isoforms bind to skin MC1-R and stimulates this.
