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Endo/Repro Exam 1 > Steroid Biosynthesis > Flashcards

Steroid Biosynthesis Flashcards

1
Q
  • Short term response by adrenal gland involves _ that release catecholamines (NE and EPI)
  • Long term response by adrenal gland involves _ that release glucocorticoids and mineralcorticoids
A
  • Nerve Impulses
  • Steroid Hormone Signaling
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2
Q
  • Steroid hormones are derived from _
A
  • Cholesterol
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3
Q
  • _ is a precursor to many steroid hormones
A
  • Progesterone
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4
Q
  • Corticosteroids
  • Sex hormones
A
  • Aldosterone and Cortisol
  • Testosterone and Estradiol
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5
Q
  • Before cholesterol is converted to progesterone, it is converted to pregnenolone via _ enzyme
  • This enzyme is found in _ tissue
  • Catalyzes the first rate limiting step
  • _ regulated by ACTH
A
  • Desmolase/CYP11A1/CytochromeP450
  • steroid producing (adrenal, testes, ovary, placenta)
  • ACTH
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6
Q
  • ACTH stimulates release of _ from the adrenal cortex
  • This feeds back to inhibit CRH release from the hypothalamus and ACTH from the anterior pituitary
A
  • Cortisol
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7
Q
  • Short term action of ACTH (seconds)
A
  • Stimulates lipoprotein uptake into cortical cells
  • Increases bioavailability of cholesterol in the adrenal cortex
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8
Q
  • What are the long term effects of ACTH (hours)?
A
  • Increased transcription of genes coding for steroidogenic enzymes:
    • P450
    • Steroid 11 beta hydroxylase
    • E- transfer proteins
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9
Q
  • ACTH and Cancer
A
  • In cancer:
    • cortisol production is uncoupled from ACTH
    • Stim of ACTH is no longer required to activate PKA and make cortisol
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10
Q
  • Progesterone
    • ​Receptor
    • Action
A
  • Binds and activates Progesterone Receptor
  • Gestation support hormone
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11
Q
  • Cortisol
    • ​Receptor
    • Action
A
  • Binds and activates glucocorticoid receptor
  • Increaes gluconeogenesis and blood pressure
  • Anti-inflammatory (EX: Dexmethasone-GR receptor agonist used to treat inflammation)
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12
Q
  • Aldosterone
    • ​Receptor
    • Action
A
  • Binds and activates mineralcorticoid receptor (MR)
  • Increases Na+ and H2O retention
  • Raises blood pressure

Synthesized in adrenal glands

Distributed to kidney tubules, colon, and parotid

Increases Na+/H2O retention, K+ excretion and blood pressure

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13
Q
  • Estradiol
    • ​Receptor
    • Action
A
  • Binds and activates estrogen receptor alpha
  • Female sex development
  • Maintenance of bone structure
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14
Q
  • Testosterone
    • ​Receptor
      Action
A
  • Binds and activates androgen receptor
  • Male sex hormone

Synthesized in adrenal glands, ovaries, and testes

Distributed to primary and secondary reproductive organs and muscles

Mediates spermatogenesis, secondary male characteristics, bone maturation, and virilization

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15
Q
  • Normal term infants versus premature infants and production of glucocorticoids
A
  • Normal term infants:
    • Burst of glucocorticoids during delivery stimulates production of surfactant and alters lung structure
  • Premature infants:
    • Process is defective-can lead to infant respiratory distress syndrome
    • Prevented by giving mother glucocorticoids
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16
Q
  • Congenital Adrenal Hyperplasia (CAH): Patient Presentation
A
  • Hirsutism-excessive body hair on parts of body where hair is normally absent (chin or chest)
  • Females also present with:
    • oligomenorrhea-infrequent menstruation
    • Infertility
  • Important because baby can be at risk for developing
    • Test w/ HLA Ag haplotype
      • Will show excess cortisol precursors in amniotic fluid
17
Q
  • Classical CAH
A
  • Simple virilizing-ambiguous genitalia in females
  • Salt wasting: dehydration, vomiting, diarrhea
18
Q
  • Non-Classical CAH
A
  • Milder
  • Androgen excess can cause precocious puberty in either sex
  • Males often undiagnosed and asymptomatic
19
Q
  • Consequences of CAH
  • Treatment for CAH
A
  • Life threatining sinus infections
  • Life threatening pulmonary infections
  • Orthostatic syncope
  • Shortened Stature
  • Severe Acne

Treat with HRT (hormone replacement therapy)

20
Q

CAH is an _ disease caused by mutations of genes that encode the enzymes of steroidogenesis

Most of these conditions involve excessive or deficient production of sex hormones

Function in adrenal glands during conversion of cholesterol to mineralcorticoids, glucocorticoids, and sex steroids

A
  • Autosomal recessive
21
Q
  • 5% of CAH cases are caused by a mutation in _
A
  • 11beta hydroxylase
  • Corticosterone precursors build up
  • Excess androgen production (male sex hormones)
  • 17 alpha hydroxy progesterone accumulation
  • HTN
    • Accumulation of 11 deoxycortisone and 11 deoxycortisol
    • 11 deoxycorticosterone Receptor MR agonist normally regulated by aldosterone
    • Promotes Na+ and H2O retention
    • Lowers Plasma K+
22
Q
  • 90-95% of CAH cases are related to a mutation in _ enzyme
A
  • 21 alpha hydroxylase
    • ​Reduced cortisol synthesis
    • Hyperplasia of adrenal cortex
    • Elevated ACTH levels (cortisol isn’t being produced, anterior pituitary makes more ACTH)
  • Hormones accumulate abnormally:
    • Increased progesterone
    • Increased 17 alpha-hydroxypregnenolone
    • Increased 17 alpha hydroxyprogesterone
  • Salt wasting
    • Lack of aldosterone (Increased Na+ loss in urine)
23
Q
  • Steroid Hormone Blood Transporter Proteins
  • Where are these synthesized?
A
  • Corticosteroid binding globulin (GBG)
  • Sex steroid binding globulin (SHBG)​
    • Partially saturated in women
    • Fully saturated by testosterone in men
  • Liver
24
Q
  • RAAS
A
25
Q
  • Pregnenolone via _, _, and _, is used to produce other steroid hormones (progesterone, aldosterone, testosterone, estradiol, cortisol)
A
  • CYPs, HSDs, Lyases
26
Q
  • More rare forms of CAH are cauesd by _ mutations
  • Show as altered primary or secondary sex characteristics in infants, children, and adults
A
  • CYP17A1
27
Q
  • ILD (Isolated 17, 20 Lyase Deficiency)
    • ​Rare, _ disorder
    • Complete or partial loss of _ activity
    • Impaired production of _ and _ sex steroids
    • _ production is not altered, so there is no adrenal hyperplasia or hypertension
  • Symptoms
A
  • AR
  • 17,20 lyase
  • Androgen and estrogen sex steroids
  • Cortisol/Aldosterone
  • Sx in males
    • Pseudohermaphroditism
    • Partially or fully underdeveloped genetalia
    • Intersex
  • Both sexes sx
    • Reduced or absent puberty
    • Lack of dev of secondary sex characteristics
    • Childlike appearance in adulthood if left untreated
28
Q
  • Regulation of hormone synthesis in the ovaries and testes
    • ​Stimulated by _
    • _ facilitates conversion of androstenedione to estrone and conversion of testosterone to estradiol
A
  • ACTH
  • FSH
29
Q
  • Regulation of steroid hormone synthesis in males and females
A
30
Q
  • Vitamin D production
    • ​Vitamin D is obtained thru _ or _
    • _ is formed exclusively in the liver by 25-hydroxylase enzyne encoded by CYP2R1 gene
A
  • Skin or diet
  • 25-hydroxycholecalciferol

Endo/Repro Exam 1 (12 decks)

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