Lecture 19

Question 1

What are your adrenals and what happens if you don’t have them?

Answer 1

Complex poly-functional organs required for life
Without it, it can lead to deranged electrolyte or carbohydrate metabolism - circulatory collapse or hypoglycemic coma and death.

Question 2

What are the 3 major categories and where are they made?

Answer 2

1) mineralocorticoids - body content of Na and K, made in zona glomerulosa (ex. aldosterone)
2) Glucocorticoids - affect body fuel metabolism, injury response and general cell functions, made in zona fasciculata (ex. cortisol)
3) Androgens - sexual differentiation hormones, made in zona reticularis (ex. androgens)

Question 3

What are the layers of the adrenal gland from outer to inner?

Answer 3

Capsule
G - zona glomerulosa (salt)
F - zona fasciculata (sugar)
R - zona reticularis (sexual differentiation)
Medulla

Question 4

Know how to draw cholesterol and how to number carbons.
How is it made and where are they stored?

Answer 4

LDLs arrive at the adrenal cortex and is taken up by receptor-mediated endocytosis. Adrenal cortical cells also synthesize cholesterol from carbohydrates or fatty acid precursors. Lots of cholesterol is stored in steroid hormone-producing cells in the form of fatty acid esters.

Question 5

• Know how to draw the pathway *
  What is the rate determining reactions in steroid hormone biosynthesis?

Answer 5

Cholesterol - (P450 SCC) -> 20-OH Cholesterol - (P450 SSC) -> 20, 22(OH)2Cholesterol - (P450 SCC) -> Pregnenolone

Question 6

What is pregnenolone used for?

Answer 6

principal adrenal steroid hormone

Question 7

• Know the structures * how is pregnenolone converted into progesterone?

Answer 7

Enzyme: 3beta-steroid dehydrogenase

Question 8

What is the pathway for steroid metabolism in zona glomerulosa?

Answer 8

pregnenolone - (3beta-steroid dehydrogenase) -> progesterone - (21-hydroxylase) -> deoxycorticosterone - (11 beta-hydroxylase & 18-hydroxylase) -> 18OH-corticosterone - (aldosterone dehydrogenase) -> aldosterone

Question 9

What is the pathway for steroid metabolism in zona fasciculata?

Answer 9

Pregnenolone - (17alpha-hydroxylase) -> 17OH-pregnenolone - (3beta-steroid dehydrogenase) -> 17OH progesterone - (21 hydroxylase) -> 11 deoxy-cortisol - (11beta-hydroxylase) -> cortisol

Question 10

What is the pathway for steroid metabolism in zona reticularis?

Answer 10

Pregnenolone - (17 hydroxylase) -> 17OH-pregnenolone - (C17/C20 lyase) -> dehydroepiandrosterone (DHEA) - (3beta-steroid dehydrogenase) -> androstenedione - (17beta- steroid dehydrogenase) -> testosterone - (aromatase) -> estrogen/estradiol