Steroid Biosynthesis

Question 1

what is the regulation of desmolase?

Answer 1

ACTH

Question 2

how is aldosterone produced?

Answer 2

in a tissue-specific manner

Question 3

what does aldosterone bind to and activate?

Answer 3

mineralocorticoid receptor (MR)

Question 4

what is MR?

Answer 4

an important nuclear receptor superfamily member

Question 5

many steroids activate MR with variable efficacy. Which hormone binds with very high efficacy?

Answer 5

11-deoxycorticosterone

Question 6

all of the hormones that activate MR increase what and cause what?

Answer 6

they all increase Na+ retention and therefore cause hypertension

Question 7

what is the syndrome associated with excessive levels of aldosterone?

Answer 7

Conn Syndrome

Question 8

what does Conn Syndrome cause?

Answer 8

excessive secretion of aldosterone, retention of sodium, loss of potassium, produces HTN

Question 9

what are the two enzymes that could be mutant in a patient with congenital adrenal hyperplasia?

Answer 9

21-hydroxylase and 11-beta hydroxylase

Question 10

what does an 11-beta hydroxylase deficiency lead to?

Answer 10

decreased aldosterone synthesis, but it produces HTN

Question 11

how does a defect in 11-beta hydroxylase cause hypertension?

Answer 11

cortisol and cortisone levels decrease because they are dependent on 11-beta hydroxylase; however, the 11-deoxycorticosterone levels increase, and this cause HTN due to its relatively high affinity for MR

Question 12

what form of vitamin d is formed only in the liver and why?

Answer 12

25-hydroxycholecalciferol; only in the liver because only the liver has 25-hydroxylase