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Biochemistry Block 3 > Steroid Hormones > Flashcards

Steroid Hormones Flashcards

1
Q

How are different classes of steroid hormones distinguished?

A

Their receptors, tissue distribution, and physiological effects

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2
Q

What do corticosteroids regulate?

A

Metabolic homeostasis

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3
Q

What are the two sub categories of corticosteroids?

A

Glucocorticoids and Mineralocorticoids

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4
Q

What effects do glucocorticoids have?

A

Anti-inflammatory, gluconeogenic

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5
Q

What is an example of glucocorticoids? WHere is it made?

A

Cortisol- adrenal cortex

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6
Q

What effects do mineralocorticoids have?

A

Stimulates uptake of salt from urine and subsequently raises blood pressure

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7
Q

What is an example of mineralocorticoids? Where is it made?

A

Aldosterone- adrenal cortex

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8
Q

What do sex hormones regulate?

A

Gender specific traits

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9
Q

Which sex hormones regulates male characteristics

A

Androgens

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10
Q

What are the androgens? Where are they synthesized?

A

Testosterone-synthesized by testes; androstenedione- adrenal glands

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11
Q

What is the precursor for estrogens?

A

Androstenedione

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12
Q

What is the function of estrogens?

A

Stimulation of female characteristics

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13
Q

What is an example of estrogens? Where is it made?

A

Estradiol- ovaries

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14
Q

What hormones regulate the reproductive cycle?

A

Progestogens

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15
Q

What is an example of progestogens? Where is it synthesized?

A

Progesterone- synthesized by corpus luteum

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16
Q

How is aldosterone carried through the blood?

A

Serum albumin

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17
Q

What carries cortisol and other steroids through the blood?

A

Corticosteroid binding globulin

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18
Q

What carries the sex hormones through the blood?

A

Sex hormone binding portein

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19
Q

Where does steroidogenesis occur?

A

matrix of the mitochondria

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20
Q

What is the precursor for all steroid hormones?

A

Cholesterol

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21
Q

What is the rate-limiting step of steroidogenesis? What enzyme catalyzes this reaction?

A

Desmolase shortens hydrocarbon chain, forming pregnenolone

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22
Q

What other molecules are required in the conversion of cholesterol to pregnenolone?

A

NADPH, O2

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23
Q

What kind of enzyme is desmolase?

A

P450 mixed function oxidase

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24
Q

Where is desmolase located?

A

Mitochondrial inner membrane

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25
How is cholesterol transported through the mitochondrial outer membrane?
Steroidogenic acute regulatory protein
26
What is the first major steroid hormone made?
Progesterone
27
What three steroid hormones can be synthesized from progesterone?
Cortisol, aldosterone, testosterone
28
What kind of genetic disorder are congenital adrenal hyperplasias?
Autosomal recessive
29
What accumulates in 3-B-hydroxysteroid dehydrogenase deficiency?
Pregnenolone
30
What are the biochemical result of 3-B-hydroxysteroid dehydrogenase deficiency?
No steroid hormones produced
31
What are the biological effects of 3-B-hydroxysteroid dehydrogenase deficiency?
Marked salt excretion in urine; all patients have female-like genitalia
32
Mutations in what two molecules lead to Lipoid Congenital adrenal hyperplasia?
Steroidogenic acute regulatory protein (StAR) or desmolase
33
What are the biological effects of Lipoid congenital adrenal hyperplasia?
Problems with BP due to salt imbalances, metabolic problems, lethargy, sex ambiguity-default to female genitalia
34
What reaction cannot be catalyzed in 17-a-hydroxylase deficiency?
Progesterone--> 17-a-hydroxyprogesterone
35
What are the biochemical results of 17-a-hydroxylase deficiency?
Virtually no sex hormones or cortisol made; increased aldosterone production leading to sodium and fluid retention and hypertension; development of female genitalia
36
What is the most common Congenital Adrenal Hyperplasia?
21-a-hydroxylase deficiency
37
What are the biochemical results of 21-a-hydroxylase deficiency?
Complete absence or deficiency of glucocorticoids, mineralocorticoids; overproduction of androgens
38
What are the biological effects of 21-a-hydroxylase deficiency?
Masculinization of female external genitalia; early virilization in males; hirsutism; short stature/early bone fusion; salt imbalances
39
What are the biochemical results of 11-B-hydoxylase deficiency?
Decreased amounts of cortisol, aldosterone, and corticosterone; increased deoxycorticosterone
40
What are the biological results of 11-B-hydroxylase deficiency?
Fluid retention; low-renin hypertension; masculization of external genitalia in females; early virilization in males
41
Where is cortisol synthesized?
Middle layer (zona fasciculata) of adrenal cortex
42
In what scenarios is cortisol upregulated?
Infection and injury
43
What is the upstream stimulation of cortisol synthesis?
Stress triggers release of corticotropin releasing hormone (CRH) from the hypothalamus which stimulates the synthesis and release of adrenocorticotropic hormone (ACTH) in anterior lobe of pituitary
44
What is Addison Disease?
Low adrenocorticotropic hormone (ACTH) production
45
What is Cushing Disease?
Elevated adrenocorticotropic hormone (ACTH) production
46
What is the mechanism of adrenocorticotropic hormone (ACTH) stimulation of cortisol production?
cAMP activation of PKA--> activation of cholesterol esterase, increased transcription of StAR
47
What is the effect of cortisol feedback on CRH and ACTH synthesis and secretion?
Inhibition
48
Where is aldosterone synthesized?
Outer layer (zona glomerulosa) of adrenal cortex
49
What induces the synthesis and secretion of aldosterone?
Low plasma Na+/K+ ratio; Angiotensin II
50
How is Angiotensin II produced?
Renin converts angiotensinogen to angiotensin I, which is converted to angiotensin II by angiotensin converting enzyme
51
What are the effects of angiotensin II
Increase in IP3 (increase in Ca2+) and DAG, activating protein kinase C, which increases aldosterone synthesis
52
In what layers of the adrenal cortex are weak androgens secreted? What are the androgens?
Inner (zona reticularis) and middle (zona fasciculata); dehydroepiandrosterone and androstenedione
53
What derivative of testosterone is 10x more potent?
Dihydrotestosterone
54
What enzyme catalyzes the conversion of testosterone to dihydrotestosterone?
5-a-reductase
55
What will a deficiency in 5-a-reductase cause?
Hermaphroditism in males due to failure to complete maturation of male genitalia
56
What is released from the hypothalamus that induces sex steroid synthesis? What molecules does this hormone directly stimulate the production of?
Gonadotropin-releasing hormone (GnRH)- Luteinizing hormone (LH) and Follicle stimulating hormone (FH)
57
What are the effects of Luteinizing Hormone?
Stimulates production of testosterone in testes, production of estrogen and progesterone in the corpeus luteum, and production of estrogen in the ovaries
58
What are the effects of Follicle Stimulating Hormone?
Regulates growth of ovarian follicles and stimulates testicular spermatogenesis
59
What is the mechanism of LH and FSH action?
Stimulation of intracellular levels of cAMP
60
What is the action of aldosterone
Stimulates renal absorption of Na+ and excretion of K+ in the kidney
61
What is the action of cortisol?
Increases gluconeogenesis, activates NFkB pathway (anti-inflammation), causes muscle protein breakdown, increases mobilization of fatty acids
62
What are the function of estrogens?
Controls menstrual cycle; promotes development of female secondary sex characteristics
63
What is the function of progesterone?
Secretory phase of the uterus and mammary glads; important for implantation and maturation of fertilized ovum
64
What is the action of testosterone?
Stimulates spermatogenesis; promotes development of male secondary sex characteristics; promotes anabolism; causes masculinization of the fetus
65
What is the location of the an un-liganded steroid hormone receptor? When bound to a ligand?
Cytosol; nucleus
66
How do steroid hormones affect DNA synthesis?
The activated hormone receptors bind to hormone response elements in the DNA, typically in enhancer regions
67
How are steroid hormones degraded?
Inactivated in the liver, made more water soluble by addition of glucuronic acid and sulfate, excreted through bile (feces) and through urine

Biochemistry Block 3 (5 decks)

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