Biochemistrysteroidhormones

Front 1

Conversion of the C27 cholesterol ring involves the rate-limiting, irreversible cleavage of

Back 1

the 6-C residue from cholesterol

Front 2

Steroids with 21 C atoms are known as

Back 2

Pregnanes

Front 3

produced from progesterone in the zona glomerulosa

Back 3

aldosterone

Front 4

an esterogen, produced in the ovary responsible for 2ndary sex characteristics

Back 4

estrodiol

Front 5

Principal mineralcorticoid

Back 5

aldosterone

Front 6

principle glucocorticoid

Back 6

cortisol

Front 7

symthesized from progesterone in zona fasciculata

Back 7

cortisol

Front 8

all steroid hormones exert action by passing through plasma membrane and binding to

Back 8

intracellular receptors

Front 9

specific nucleotide sequences bing to hormone-receptor complexes

Back 9

Hormone response elements HREs

Front 10

Leutinizing hormone stimulates sythensis of

Back 10

progesterone
testosterone

Front 11

ACTH hormone stimulates sythensis of

Back 11

cortisol

Front 12

FSH hormone stimulates sythensis of

Back 12

estradiol

Front 13

Angiotensin I and II stimulates sythensis of

Back 13

aldosterone

Front 14

committed and reat-limiting step of steroid synthesis

Back 14

cleavage of a 6-carbon group from cholesterol

Front 15

the NZ system catalysing the 6-C group is the

Back 15

P450 linked side cleavage NZ

Front 16

P450 sc or desmolase is found in the __________ of steroid producing cells

Back 16

mitochondria (not in significant quantities in other cells)

Front 17

desmolase consists of cyt P450 and

Back 17

adrenadoxin (a P450 reductant)

Front 18

Desmolase
1) cAMP stimulates PKS - leads to

Back 18

phosphorylation of cholesterol-ester esterase
↑ concentrations of cholesterol

Front 19

Desmolase
2) gene for desmolase contain cAMP regulated reg. element CRE binds cAMP and ____

Back 19

↑ levels of desmolase RNA transcription
↑ levels of NZ

Front 20

Cholesterol is a NEGATIVE feedback regulator of HMG CoA reductase activity. When cytosolic cholesterol is depleted ____

Back 20

de novo synthesis of cholesterol is stimulated
HMG CoA reductase is freed of restraints

Front 21

Subsequent to desmolase activity, prenenolone ____

Back 21

moves to cytosol - further processed

Front 22

hydroxulases involved in synthesis of steroid hormones are members of

Back 22

Cyt P450 Nzs
Indictes site of hydroxylation
eg. P450c17

Front 23

Adrenal cortex produces 3 major classes of steroid hormones

Back 23

glucocorticoids
mineralcorticoids
androgens

Front 24

Adrenal insufficiency is know as

Back 24

Addison's disease

Front 25

Zona glomerulosa cells lack P450c17 that converst pregnenolone and

Back 25

progesterone to C17 hydroxylated analogs

Front 26

Zona glomerulosa
pathways to glucocorticoids (___) and andgrogens (____) are blocked

Back 26

deoxycortisol and cortisol
DHEA and androstenedione

Front 27

Zona glomerulosa
unique - contain NZ that converts corticosteron to

Back 27

aldosterone - principal mineralcorticoid

Front 28

The NZ P450c18 or 18a-hydeoxylase is also called

Back 28

aldosterone synthase

Front 29

Zona Fasciculata and Zona reticularis lack P450c18 and cannot convert corticosterone to

Back 29

aldosterone

Front 30

Zona Fasciculata and Zona reticularis contain P450c17 and produce

Back 30

cortisol - the major glucocorticoid

Front 31

Zona Fasciculata and Zona reticularis contain C17, 20 lyase whose activity is resp. for producing

Back 31

the androgens
DHEA
androstenedione

Front 32

P450ssc is converted to androgens or
11-deocycortisol and
11-deoxycorticosterone by NZs in the

Back 32

Endoplasmic reticulum

Front 33

P450ssc
after conversion - renter the ______ and NZs convert to

Back 33

mitochondria
glucocorticoids
mineralcorticoids

Front 34

ACTH of hypothalamus
regulates hormone production of

Back 34

Zona Fasciculata
Zona Reticularis

Front 35

ACTH receptors in the plasma membrane activates

Back 35

aednylate cyclase → 2nd messenger cAMP

Front 36

ACTH - clssic feedback loop CRH
ACTH
and

Back 36

cortisol

Front 37

Mineralcorticoid secretion from the _____

Back 37

zona glomerulosa

Front 38

Kidney protease acts on → Angoistensinogen from liver → stim zona glom cells by binding plasma membrane receptor coupled to

Back 38

Phospholipase C

Front 39

This angiotensin II and III bind to their receptors → leads to activation of _____ and elevated ______

Back 39

activates PKC
↑ intracellular Ca++
↑ P450 SSC
↑ aldosterone

Front 40

In the kidney aldosterone regulates Na+ retention by stimulating gene expression of

Back 40

mRNA for Na+/K+ ATPase responsible for re-accumulation of Na+ from urine

Front 41

Drugs widely used to lower blood pressure

Back 41

ACE inhibitors

Front 42

ACE inhibits compete with

Back 42

NZ that convert angiotensis I to active angiotensin II and III

Front 43

Feedback loop of ACE imhibitors os closed by

Back 43

K+ - potent stimulator of aldosterone

Front 44

K+ increases aldosterone secretion by depolarizing the plasma membrane of _____ opening voltage gated

Back 44

Zona glomerusola cells - Ca++ channel
↑ cytoplasmic Ca++and stimulation of Ca++ dep processes

Front 45

Low levels of of circulating sex hormones reduce the _____ and lead to elevation of FSH and LH

Back 45

feedback inhibition of GnRH synthsis (long loop)

Front 46

FSH and LH bind to gonad tissue and stimulate P450SSC activity resulting in sex hormone production via

Back 46

cAMP
PKA mediated pathways

Front 47

Andenylate cyclase activation is coupled to the binding of

Back 47

LH to plasma membrane receptors

Front 48

testes and ovaries contain an additional NZ ______ that enables androgens to be converted to

Back 48

17bHSD
testosterone

Front 49

In males LH binds to ___ cells and stimulates _____

Back 49

Leydig
testosterone

Front 50

Testosterone is secreted into the plasma and also carried in the ____ cells by ________

Back 50

Sertoli
Androgen Binding proein (ABP)

Front 51

In Sertoli cells the D4 double bond of testosterone reduced producing

Back 51

dihydrotestosterone (DHT)

Front 52

testosterone and DHT are carried in the plasma and delivered to tissues by

Back 52

gonadal-steroid binding globulin (GBG)

Front 53

In some tissues testosterone can be converted to DHT - the most ______

Back 53

potent of the male steroid hormone
(testosterone sometimes considered a prohormone)

Front 54

Testosterone can also be produced int the ____ cells, but it is regulated by _____

Back 54

Sertoli
FSH

Front 55

FSH also stimulates Sertoli cells to produce ____ which transports Testosterone and DHT from ____ to ______

Back 55

APB
Leydig cells to sites of
spermatogenesis

Front 56

There testosterone acts to stimulate

Back 56

sperm development and
proten synthesis

Front 57

In females, LH binds to ______ where is stimulates synth of ______ by the usual

Back 57

thecal cells of the ovary
androstenedione and testosterone
cAMP and PKA reg pathways

Front 58

Aromatase is responsible for the final ____

Back 58

conversion of into estrogen

Front 59

Aromatase
complex NZ in ______ found in the

Back 59

ER
ovary and other tissues

Front 60

Aromatase
its hydroxylations and dehydrations culminate in the ____

Back 60

aromatization of the A ring of androgens

Front 61

Synthesis of testosterone and androstenedione occurs from _______

Back 61

cholesterol

Front 62

Aromatase activity is also found in ______ but the activity is stimulated by

Back 62

granulosa cells
FSH

Front 63

Normally thecal cell androgens are produced in response to ______ and diffuse to _________

Back 63

LH
granulosa cells

Front 64

Granulosa cell aromatase converts androgens to ____-

Back 64

estrogens

Front 65

As granulosa cells mature they develop a large number of _____ receptors in the _____ ↑ wuantity of estrogen produced

Back 65

LH
plasma membrane

Front 66

granulosa cell estrogens are largely secreted into

Back 66

follicular fluid

Front 67

Thecal cell estrogens are secreted into the ____ where they are delivered to taget tissues by

Back 67

circulation
GBG (also used to transport testosterone

Front 68

The binding of hormone, and/or phosphorylation of receptor Heat Schok Proteins (HSP) initiate movemnt of

Back 68

nuclear receptor to the nucleus

Front 69

HREs are on the DNA in the

Back 69

promoter egion

Front 70

The hormone receptor complex often binds as homodimer to _____ and bends the DNA at the _______

Back 70

palindromically oriented HREs
site of binding

Front 71

Disaggregation - hormone level falls - movement of receptor back to _____ where ____ can bind

Back 71

cytoplasm
HSPs

Front 72

The steroid and thyroid family of receptors have three distinct domains

Back 72

a ligand binding region
a DNA binding domain and
a transcriptional reg domain

Front 73

Binding of thyroid hormone to its receptor results in

Back 73

release of rceptor from the DNA

Front 74

Binding of glucocorticoid leads to _____ of ligand-binding receptor from cytosol to ____

Back 74

translocation
nucleus

Front 75

The receptors for the retinoids are ID as _____ and have three subtypes

Back 75

RARs