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physio fall midterm > endocrinology lecture 4 > Flashcards

endocrinology lecture 4 Flashcards

1
Q

sex steroids are secreted by what…

A
  • adrenal cortex
  • placenta
  • gonads aka testis and ovary
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2
Q

what are the 3 major classes of sex steroids?

A
  1. pregnanes (21 C)
  2. androgens/androstanes (19 C)
  3. estrogens/estranes (18 C)
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3
Q

what determines the 3 major classes of sex steroids

A

the number of carbons they contain

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4
Q

what is the primary male hormone?

A

Testosterone (member of the androgens)

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5
Q

True or False: T is more potent than DHEA and androstenedione

A

TRUE; however, it is not the most potent androgen… DHT is the most potent androgen

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6
Q

what enzyme converts T to DHT?

A

5alpha-reductase

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7
Q

what are the primary female hormones?

A
  • progesterone (P), a progestin

- estradiol (E2), an estrogen

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8
Q

True or false: steroids are hydrophilic hormones

A

FALSE; they are LIPOPHILIC, hence they can’t be stored

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9
Q

why is GnRH secretion from the hypothalamus pulsatile?

A

pacemaker neurons that spontaneously produce action potentials –> results in secretory bursts of GnRH

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10
Q

what hormones are the anterior pituitary have a pulsatile release in response to bursts of GnRH from the hypothalamus?

A 
Luteinizing hormones (LH)
follicle stimulating hormone (FSH)
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11
Q

True or False: the pulsatile nature of GnRH stimulation is necessary for gonadotropin secretion

A

TRUE; continuous, non-pulsatile GnRH downregulates GnRH receptors in the anterior pituitary, inhibiting LH and FSH secretion

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12
Q

gonadal steroids exert __________ feedback control of GnRH and LH secretion.

A

negative

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13
Q

E2 has __________ feedback actions on __________ secretion prior to ovulation

A

positive; LH

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14
Q

activation of steroid receptors regulates what…

A

gene transcription; in gonads, these genes regulate gametogenesis and hormone synthesis

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15
Q

Gonadal steroids regulate protein synthesis in what other reproductive organs?

A
  • male accessory glands
  • uterus
  • breasts
  • brain
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16
Q

what are the 3 important reproductive cells in the testis?

A
  1. spermatic cells/gametes
  2. Leydig cells/interstitial
  3. Sertoli/sustenacular cells
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17
Q

spermatic cells include what…

A

active spermatogonia (diploid) and meiotic spermatocytes (haploid)

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18
Q

True or False: Leydig cells lie outside of the seminiferous tubules

A

True

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19
Q

Leydig cells synthesize _______ in response to _______

A

Testosterone (T); LH

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20
Q

In the gonad, T regulates _______

A

spermatogenesis

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21
Q

In the brain, T regulates _______

A

sexual behavior (after T is aromatized to E2)

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22
Q

In response to _______, sertoli cells regulate spermatogenesis and produce what

A

FSH; the peptide hormone inhibin

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23
Q

True or False: inhibin has positive feedback actions on FSH secretion

A

FALSE; it has NEGATIVE feedback actions that are independent of androgen negative feedback effects

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24
Q

Sertoli cells produce an androgen binding proteins that helps sequester what hormone?

A

Testosterone! this allows spermatogenesis to be continuous

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25
Q

Testicular steroidogenesis: 2 cells & 2 gonadotropins

A

testicular endocrine function involves two cells, Leydig and Sertoli, that each respond to one of the two gonadotropins, LH and FSH

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26
Q

Peripherally, T is converted to what steroid? 2 answers

A
  1. dihydrotestosterone (DHT) by 5alpha reductase; DHT is a very potent androgen
  2. estradiol (E2) or androstenedione –> estrone by aromatase; takes place in brain and bone
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27
Q

_______ are used to treat breast and prostate cancers

A

aromatase inhibitors; both of these types of cancer are estrogen dependent

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28
Q

_______ are used to treat hair loss

A

5alpha reductase inhibitors

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29
Q

DHT promotes what in men

A

hair loss by inactivating hair follicles (sorry fellas)

30
Q

what other effects of T are important in females? (3)

A
  1. regulate bone growth: interacts with GH
  2. stimulate muscle growth: anabolic steroid
  3. stimulate erythropoiesis
31
Q

what is andropause?

A

the male counterpart to menopause (who knew???); associated with increase in emotional disorders with aging but men still remain fertile (enjoy being fathers at age 70 guys)

32
Q

what are the 4 important reproductive cells in the ovary?

A
  1. oocytes (enclosed in ovarian follicle)
  2. theca cells
  3. granulosa cells
  4. luteal cells
33
Q

shortly after birth, all oocytes are arrested in which phase

A

prophase of meiosis I

34
Q

which female reproductive cells are analogous to leydig cells in the male?

A

Theca cells

35
Q

grunulosa cells in the female are analogous to which male reproductive cell type?

A

sertoli cells

36
Q

granulosa cells continue to surround the oocyte in what

A

the cumulus oophorus

37
Q

what do granulosa cells do?

A

regulate oocyte development and convert testosterone to estradiol

38
Q

True or False: luteal cells are present before ovulation

A

FALSE; they are present after ovulation when theca and granulosa cells become the cells of the corpus luteum

39
Q

which hormones do luteal cells make

A

progesterone and estradiol

40
Q

theca cells synthesize _______ in response to _______

A

androstenedione (diffuses into granulosa cells); LH

41
Q

In response to FSH, granulosa cells do what

A
  1. convert androstenedione to estrone –> estradiol (this conversion stimulates granulosa cell function and replication, regulates oocyte development and female secondary sex characteristics, regulates bone turnover and arterial function and inhibits GnRH and LH secretion)
  2. secrete inhibin (which has a negative feedback effect on FSH secretion)
42
Q

True or False: larger follicles have more LH and FSH receptors

A

TRUE; thus, they produce greater amounts of estradiol and inhibin

43
Q

ovarian cycle

A

Days 1 & 2: gonadotropin rise and follicular development
Days 3-5: increase estradiol and inhibin (inhibits FSH); dominant follicle selection
Days 6-8: FSH decrease, estradiol peak, LH surge (positive feedback action of E2 on GnRH and LH)
*end follicular phase
Days 9-11: meiosis I completed, ovulation, and CL formation (beginning of luteal phase)
Days 12-13: Increase estradiol and P (progesterone), inhibit gonadotropins
Days 14-16: CL regression, decrease steroids, gonadoptropins rise

44
Q

menstrual/uterine cycle

A

menstrual phase: begins when the CL regresses and steroid support for uterine endometrium is lost

proliferative phase: follicular estradiol stimulates proliferation of the endometrium

45
Q

during the luteal phase, _____ and _____ stimulate uterine secretory activity

A

P and estradiol –> this increases glandular production of glycogen and angiogenesis and decreases contractility

46
Q

If pregnancy occurs (oh dear god), the placenta produces which hormone

A

human chorionic gonadotropin (hCG)

47
Q

what does human chorionic gonadotropin do

A

similar to LH; maintains luteal steroidogenesis until placenta fully develops

48
Q

what happens in menopause

A

cessation of menstrual cycles due to ovarian failure

49
Q

what are the hormonal consequences of menopause (3)

A
  1. lose ovarian steroids
  2. loss of inhibin, gonadotropin is very high
  3. increase reliance on adrenal steroids
50
Q

how is differentiation of gonadal sex determined

A

the presense of a gene on the Y chromosome that encodes for SRY protein –> directs indifferent gonad to become a testis

51
Q

which 2 hormones are produced by the fetal testis

A

T and Mullerian inhibiting substance (MIS)

52
Q

what are the 2 sets of tubules associated with the developing gonad

A

wolffian and mullerian ducts

53
Q

in the developing male, T stimulates proliferation of which duct system

A

wolffian duct system; will become tubules associated with the male reproductive tract; MIS causes mullerian system to regress

54
Q

in the developing female, absence of T causes what

A

regression of the wolffian duct system; absence of MIS results in proliferation and maintenance of Mullerian system

55
Q

the early embryo and fetus are undifferentiated p to how many weeks of gestation

A

9 week

56
Q

_______ from the developing testis stimulate differentiation of male external genitalia

A

androgens (most T converted to DHT)

57
Q

in the male, the genital tubercle becomes what

A

glans of penis

58
Q

in the male, the urogenital fold becomes what

A

urethra and surrounding penis

59
Q

in the male, the labioscrotal folds become what

A

scrotum and skin of penis

60
Q

_______ stimulates the development of female external genitalia

A

absence of androgens

61
Q

in the female, genital tubercle becomes what

A

glans of clitoris

62
Q

in the female, urogenital fold becomes what

A

labia minor and urethral opening

63
Q

in the female, labioscrotal fold becomes what

A

labia majora

64
Q

what causes sexual differentiation of the brain in the devleoping male (very general)

A

T aromatized to estradiol (E2)

65
Q

congenital adrenal hyperplasia

A

adrenal enzyme deficiency results in excess production of adrenal androgens; genotype is XX but phenotype is more male than female; wolffian duct persists bc of excess androgens, mullerian duct persists bc no MIS

66
Q

5alpha reductase deficiency aka guevodoces

A

since development of penis, scrotum and prostate gland is DHT dependent, enzyme deficiency results in failure of differentiation of external genitalia early in life; increase T secretion with onset of puberty completes differentiation; genotype is XY but phenotype is female at birth until puberty; wolffian system persists bc making MIS, mullerian system regresses

67
Q

Testicular feminization/androgen insensitivity

A

lack of functional androgen receptor –> no differentitation of genitalia; genotype is XY but phenotype is FEMALE; no wolffian system or mullerian system

68
Q

True or False: there is a dramatic decrease in circulating concentrations of steroid hormones during pregnancy

A

FALSE; there is a dramatic increase due to placental production

69
Q

what stimulates growth of myometrium

A

placental E2

70
Q

placental P does what

A

reduces uterine contractility and stimulates vasodilation (increase blood flow to fetus)

71
Q

True or False: pregnant women are more susceptible to gingivitis and periodontitis

A

True

physio fall midterm (12 decks)

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