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Endocrine > steroid biosynthesis > Flashcards

steroid biosynthesis Flashcards

1
Q

is endocrine signaling long or short lasting

A

long lasting

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2
Q

lypophilic signaling molecules: steroid hormones

A

steroid hormones: progesterone, estradiol, testosterone, vitamin D, aldosterone, cortisol

(PET VAC)

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3
Q

lipophilic hormones 3 classes

A

steroid hormones
thyroid hormones
retinoids

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4
Q

lipophilic signal molecules: thyroid hormones

A

thyroxine

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5
Q

lipophilic signal molecules retinoids

A

retinol, retinoic acid

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6
Q

3 parts of intracellular receptors

A

DNA binding domain, ligand-binding domain, and txn-activating domain

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7
Q

what are steroid hormones synthesized from ___ in ___ and where

A

cholesterol in the smooth ER of adrenal cortex, ovaries, and testes

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8
Q

where do adrenal cortex, ovaries, and testis get cholesterol from

A

circulating LDL
de novo synthesis from acetyl coA
from cholesterol esters stored in cytoplasmic lipid droplets

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9
Q

acetyl coA pathway with steroids

A

acetyl coA X 3 = IPP
IPP can form
steroids, lipid soluble vitamins, ubiquinone, heme tails

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10
Q

how many IPPs do you need to make vitamin D

-how many carbons is it

A

6 unit, 27 carbons

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11
Q

what is the RL step of steroid hormone synthesis

A

cholesterol to pregnenolone

desmolase is enzyme used

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12
Q

what is a stimulator of desmolase

A

ACTH activates expression

LH increases activity

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13
Q

pregnenolone effects without conversion

A
  • works as modulator of NT signaling in brain

- effects NMDA gluatamte receptor (memory and learning)

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14
Q

glucocorticoids have affinity for ___ receptors and are 100 times more concentrated

A

mineralcorticoid

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15
Q

what must pregnenolone be converted to to make other progestrogens and what enzymes are responsible

A

progesterone

-17a hydroxlase and 3-B hydroxysteroid dehydrogenase

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16
Q

progesterone is specifically converted in a tissue specif manner to

A

aldosterone, cortisol, estradiol and testosterone

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17
Q

estradiol comes from where

A

testosterone in ovaries, minor amt in adrenal cortex

18
Q

what is formed along with testosterone in the testes and is more potent

A

dihydrotestosterone

19
Q

conversion of testosterone to estradiol enzyme and stimulatory factor

A

testosterone —-aromatase—> estradiol

-occurs in ovaries, FSH is positive stimulator

20
Q

where is desmolase found

A

only in tissues that produce steroid hormones

gonads, and adrenal cortex

21
Q

21-hydroxylase deficiency

A

hyponatremia, hypoglycemia

-in females causes virilism (development of male secondary characterisitcs)

22
Q

if have a deficiency of 17-a hydroxylase this causes what?

can be compensated by what

A

loss of cortisol and sex steroids

-decrease in cortisol is compensated by increased production of corticosterone (aldosterone arm)

23
Q

defect in 11-B hyrdroxylase

A

causes hypertension due to accumulation of 11-decoxycorticosterone which has mineralcorticoid like effects

24
Q

how does cortisol suppress immune system

A

induce production of i-kBa which helps keep NF-kB inactive in cytoplasm

  • NF-kB is required for cytokines like IL-2 needed for T cell prolif
  • Cortisol promotes T cell apoptosis
  • decreased IL-2 and its receptor lead to inhibtion of clonal expansion of B lymphocytes as well
25
Q

kidneys colon and parotid gland have receptor that has equal affinity for both mineralo and glucocorticoids, how does this tissue deal with this to prevent Na+/H20 retention

-licorice effect

A

Cortisol metabolized to cortisone by 11B-hydroxysteroid dehydrogenase

  • cortisol has lower affinity for mineralocorticoid receptor
  • licorice root contains isoflavones which inhibit this enzyme which can lead to hypertension
26
Q

testosterone converted to DHT by what
-DHT has an ___ affinity for androgen receptor than testosterone
what drug inhibits the enzyme for this conversion and it treats what

A

testosterone —-5-a-reductase–> DHT

  • DHT has higher affinity than testosterone for androgen receptor
  • finasteride inhibits 5-a reductase
  • used to treat beningn prostatic hyperplasia and male pattern baldness
27
Q

vitamin D2,D3, calcitriol

A

Vitamin D2,D3 can come from diet

  • Vitamin D3 produced in skin from sunlight
  • Calcitriol, active form of Vitamin D, derived from D2 and D3
28
Q

what stimulates calcitriol

what inhibits it

A

stimulated by PTH

inhibitied by calcitonin

29
Q

PTH on calcitriol causes what

A

increased calcium and phosphate absorption from intestinal lumen
increased bone resorption
increased calcium reabsorption in kidneys

-overall increases phosphate and calcium

30
Q

examples of glucocorticoids

A

cortisol, cortisone, corticosterone

31
Q

examples of mineralocortiocis

A

aldosterone, 11-deoxycorticosterone

32
Q

examples of estrogens

A

estradiol and estrone

33
Q

examples of androgens

A

testosterone, DHEA, 5-DHT

34
Q

what substrate is converted into aldosterone, what is the enzyme, and what stimulates this

A

corticosteron—-18-hyrdoxylase—>aldosterone

(+) angiotensin II

35
Q

what is vitamin D derived from

A

cholesterol

36
Q

vitamin D3 is converted from what by sunlight

A

7-dehydrocholesterol

37
Q

what stimulates 1-a-hydroxylase

A

PTH, low phosphate, low calcium

38
Q

what inhibits 1-a-hydroxylase

A

calcitorl (increased vitamin D has neg feedback)

39
Q

glucocorticoids and infant RDS

A

in premature babies there is no burst of glucocorticoids to have type II alveolar cells make surfacant
-leads to infant RDS and give expecting mother glucocorticoids to treat

40
Q

progesterone and pregnancy

A

progesterone supports pregnancy, embryogenesis and involved in maintenance of menstrual cycle

  • regulates calcium channels on spermatozoa
  • prepares uterus for implantation
  • increases SM relaxation
  • decreases maternal immune response
  • prog decreases before period, labor, lactation
41
Q

steroid hormones and globulins

A

CBG transports: plasma glucocorticoid hormones, and progesterone

SHBG transports: testosterone, DHT, and estradiol

  • partially saturated with estradial in women
  • fully saturated with testosterone in men

Endocrine (14 decks)

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