Steroid Metabolism Flashcards Preview

Biochemistry Post Midterm > Steroid Metabolism > Flashcards

Flashcards in Steroid Metabolism Deck (38):
1

What are the 5 classes of steroids?

glucocorticoids
mineralcorticoids
androgens
estrogens
progestins

2

where does synthesis and secretion of steroids occur?

adrenal cortex (cortisol, aldosterone)
ovaries and ovarian corpus luteum (estrogen and progestins)
testes (testosterone)

3

What are steroid hormones and what do they use in the blood?

hydrophobic
carrier proteins

4

what are the carrier proteins?

transcortin for cortisol
sex-hormone binding protein - sex hormones
can be carried non-sepcifically by albumin

5

how is cholesterol that is used for steroid hormone synthesis take up?

LDL or HDL or its synthesized

6

How is cholesterol stored?

cholesterol ester (CE)

7

what is an important regulatory step of cortisol synthesis?

transport of cholesterol into the mitochondria

8

What transport of cholesterol into the mitochondria ?

StAR (steroidogenic acute regulatory protein)

9

what activates cholesterol esterase?

PKA

10

what is the rate limiting enzyme of steroid hormone synthesis?

desmolase

11

what does desmolase require?

NADPH and O2

12

what oxidizes and isomerizes pregnenolone to progesterone?

3-beta-hydroxysterioud DH

13

what are the names for desmolase?

cholesterol side chain cleavage enzyme
CYP 11A1
P450 scc

14

What are most enzymes (hydroxylases) ins teroid synthesis dependent on?

cytochrom P450 enzymes

15

what does z. glomerulosa release?

aldosterone

16

what does z. fasciculata release?

cortisol

17

what does z. fasciculata and z. reticular is release?

androgens, DHEA, androstenedione

18

what stimulates the production of cortisol?

ACTH

19

what stimulates the production of aldosterone?

angiotensin II/III

20

what stimulates the production of estadiol?

FSH

21

what stimulates the production of progesterone and testosterone?

LH

22

how is cortisol synthesized?

from progesterone in the z. fasciculata of adrenal cortex

23

what is cortisol needed for ?

gluconeogenesis

24

what does cortisol lead to?

general degradation of muscle protein - counteracts the action of INSULIN

25

what does cortisol inhibit?

receptor activated phospholipase A2
induction of COX-2

26

how is cortisol transported in blood (%)?

75% to transcortin
15% to albumin

27

what makes aldosterone?

produced from progesterone in the z. glomerulosa

28

what are the main androgens?

DHEA and androstenedione

29

what are weak androgens changed in fat cells to?

estradiol in peripheral tissue to testosterone

30

what activates testosterone synthesis?

LH receptors in leydig cells increase c-AMP and PKA

31

what do sertoli cells produce?

Di hydrotestosterone (DHT) - more potent that testosterone

32

what is cushing syndrome due to?

hyperfunction of the adrenal cortex to due adrenocorticol tumor

33

what levels of cortisol and ACTH are found in cushing syndrome?

high cortisol
low ACTH in plasma
*high cortisol in urine

34

what does glucocorticoid excess lead to in cushing syndrome?

protein loss and to characteristic fat distribution

35

what happens to the adrenal cortex in Addisons disease?

atrophy
by autoimmune destruction

35

what happens to the adrenal cortex in Addisons disease?

atrophy
by autoimmune destruction

36

what are the levels of aldosterone, cortisol and ACTH in addison's disease?

aldosterone = low
cortisol = low
ACTH = high

36

what are the levels of aldosterone, cortisol and ACTH in addison's disease?

aldosterone = low
cortisol = low
ACTH = high