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Biochemistry Post Midterm > Steroid Metabolism > Flashcards

Steroid Metabolism Flashcards

1
Q

What are the 5 classes of steroids?

A 
glucocorticoids
mineralcorticoids
androgens
estrogens
progestins
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2
Q

where does synthesis and secretion of steroids occur?

A 
adrenal cortex (cortisol, aldosterone)
ovaries and ovarian corpus luteum (estrogen and progestins)
testes (testosterone)
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3
Q

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

A

hydrophobic

carrier proteins

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4
Q

what are the carrier proteins?

A

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

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5
Q

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

A

LDL or HDL or its synthesized

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6
Q

How is cholesterol stored?

A

cholesterol ester (CE)

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7
Q

what is an important regulatory step of cortisol synthesis?

A

transport of cholesterol into the mitochondria

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8
Q

What transport of cholesterol into the mitochondria ?

A

StAR (steroidogenic acute regulatory protein)

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9
Q

what activates cholesterol esterase?

A

PKA

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10
Q

what is the rate limiting enzyme of steroid hormone synthesis?

A

desmolase

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11
Q

what does desmolase require?

A

NADPH and O2

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12
Q

what oxidizes and isomerizes pregnenolone to progesterone?

A

3-beta-hydroxysterioud DH

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13
Q

what are the names for desmolase?

A

cholesterol side chain cleavage enzyme
CYP 11A1
P450 scc

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14
Q

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

A

cytochrom P450 enzymes

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15
Q

what does z. glomerulosa release?

A

aldosterone

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16
Q

what does z. fasciculata release?

A

cortisol

17
Q

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

A

androgens, DHEA, androstenedione

18
Q

what stimulates the production of cortisol?

A

ACTH

19
Q

what stimulates the production of aldosterone?

A

angiotensin II/III

20
Q

what stimulates the production of estadiol?

A

FSH

21
Q

what stimulates the production of progesterone and testosterone?

A

LH

22
Q

how is cortisol synthesized?

A

from progesterone in the z. fasciculata of adrenal cortex

23
Q

what is cortisol needed for ?

A

gluconeogenesis

24
Q

what does cortisol lead to?

A

general degradation of muscle protein - counteracts the action of INSULIN

25
Q

what does cortisol inhibit?

A

receptor activated phospholipase A2

induction of COX-2

26
Q

how is cortisol transported in blood (%)?

A

75% to transcortin

15% to albumin

27
Q

what makes aldosterone?

A

produced from progesterone in the z. glomerulosa

28
Q

what are the main androgens?

A

DHEA and androstenedione

29
Q

what are weak androgens changed in fat cells to?

A

estradiol in peripheral tissue to testosterone

30
Q

what activates testosterone synthesis?

A

LH receptors in leydig cells increase c-AMP and PKA

31
Q

what do sertoli cells produce?

A

Di hydrotestosterone (DHT) - more potent that testosterone

32
Q

what is cushing syndrome due to?

A

hyperfunction of the adrenal cortex to due adrenocorticol tumor

33
Q

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

A

high cortisol
low ACTH in plasma
*high cortisol in urine

34
Q

what does glucocorticoid excess lead to in cushing syndrome?

A

protein loss and to characteristic fat distribution

35
Q

what happens to the adrenal cortex in Addisons disease?

A

atrophy

by autoimmune destruction

35
Q

what happens to the adrenal cortex in Addisons disease?

A

atrophy

by autoimmune destruction

36
Q

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

A 
aldosterone = low
cortisol = low
ACTH = high
36
Q

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

A 
aldosterone = low
cortisol = low
ACTH = high

Biochemistry Post Midterm (24 decks)

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