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Endocrinology -- Freedman > Final Exam-- Hormones of Reproduction > Flashcards

Final Exam-- Hormones of Reproduction Flashcards

1
Q

What are the three ways that “maleness” and “femaleness” can be characterized?

A
  1. Genetic sex (XX, XY)
  2. Gonadal sex (testis or ovaries)
  3. Phenotypic sex (genital sex– external genitalia)
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2
Q

What determines the Genetic sex?

A

sex chromosomes

  • XX in females
  • XY in males
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3
Q

How long are gonads indifferent/bipotential in the fetus?

A

through week 5

neither male or female

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4
Q

What week in fetus do testes begin to develop?

A

6-7 weeks

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5
Q

What week in the fetus do ovaries in females begin to develop?

A

week 9

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6
Q

T/F. Genetic sex always determines gonadal sex

A

FALSE– Genetic sex USUALLY determines gonadal sex

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7
Q

What features is gonadal sex determined by?

A

males–> testes

females–> ovaries

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8
Q

How many cell types do the gonads consists of?

A

three

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9
Q

What are the three cell types the Testes consists of?

A
  1. Germ cells
  2. Sertoli cells
  3. Leydig cells
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10
Q

What are the three cell types the Ovaries consists of?

A
  1. Germ cells
  2. Theca cells
  3. Theca + Granulosa cells
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11
Q

What cells in the testes produce spermatogonia?

A

Germ cells

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12
Q

What cells in the testes synthesize antimullerian hormone and inhibin?

A

Sertoli cells

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13
Q

What cells in the testes synthesize testosterone?

A

Leydig cells

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14
Q

What cells in the ovaries produce oogonia?

A

germ cells

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15
Q

What cells in the ovaries synthesize progesterone?

A

theca cells

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16
Q

What cells in the ovaries synthesize estrogen?

A

Theca + Granulosa cells

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17
Q

What hormones need to be present in order to create a male genital tract and external genitalia?

A

Antimullarian hormone (from Sertoli cells)

Testosterone (from Leydig cells)

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18
Q

What hormones need to be present in order to create a female genital tract and external genitalia?

A

it is the ABSENCE of antimullarian hormone and testosterone

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19
Q

What is phenotypica sex defined by?

A

physical characteristics of internal genital tract and external genitalia

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20
Q

What does the internal genital tract for males consist of? What about the external genitalia?

A

prostate, seminal vesicle, vas deferenes, epididymis

scrotum, penis

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21
Q

What does the internal genital tract for females consist of? What about the external genitalia?

A

uterine tubes, uterus, upper 1/3 of vagina

clitoris, labia majora, labia minora, lower 2/3 of vagina

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22
Q

What stimulates growth and differentiation of the Wolffian ducts in the fetus? What do they differentiate into?

A

testosterone

epididymis, vas deferens, seminal vesicles, and ejaculatory ducts

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23
Q

What causes atrophy of the mullerian ducts?

A

Antimullerian hormone

which would become female parts

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24
Q

What does growth and development of the external genitalia in the male during wks 9-10 depend on?

A

conversion of testosterone to dihydrotestosterone and androgen receptors

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25
Q

What aren’t the wolffian ducts stimulate in the female?

A

since the ovaries DO NOT produce testosterone

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26
Q

What are the ducts called that differentiate into the females parts? What parts of the internal female tract do they differentiate into?

A

Mullerian ducts–> into uterine tubes, upper 1/3 of vagine

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27
Q

What hormones are required for the female genitalia? What is required for growth of the structures to normal size?

A

NONE for them to differentiation

to normal size requires estrogen

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28
Q

What is it called when someone has a male genotype but a female phenotype?

A

Androgen Insensitivity Syndrome

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29
Q

When is Andorgen Insensitivity Syndrome discovered?

A

when a female at puberty shows breast development but no menstruation

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30
Q

What will a pelvic exam of someone with Androgen Insensitivity Syndrome show?

A

presence of testes and a short vagina

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31
Q

What is occur at the binding level of someone with Androgen Insensitivity Syndrome?

A

no binding of testosterone or dihydrotestosterone –> the androgen receptors absent/defective

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32
Q

What hormones will be elevated in someone with Androgen Insensitivity Syndrome?

A

elevated levels of testosterone and LH

due to neg. feedback suppression not being able to occur due to defective androgen receptors

33
Q

What internal organs are absent in someone with Androgen Insensitivity Syndrome? What will they never have?

A

no uterine tubes, uterus, or upper vagina–> will never have menstrual cycles/pregnancy

34
Q

What do the testes secrete in someone with Androgen Insensitivity Syndrome in utero? What does this cause?

A

both antimullerian hormone and testosterone

  • suppression of mullerian ducts (hence no menstruation)
  • but targets are unresponsive to testosterone–> therefore male genital tract and external genitalia failed to develop (female genitalia by default)
35
Q

Why would someone with Androgen Insensitivity Syndrome have breast development?

A

due to high levels of LH stimulating testes producing estradiol from testosterone

estradiol promotes breast development

36
Q

What is the Tx for someone with Androgen Insensitivity Syndrome?

A

removal of testes to prevent neoplasm after puberty (source of estrogen is now gone)

intermittent estrogen replacement therapy

37
Q

What is the hormonal secretion driven by in both males and females?

A

hypothalamic-pituitary axis

38
Q

What hormone is secreted beginning at week 4 of gestation?

What is secreted beginning b/w weeks 10-12?

A

GnRH

FSH/LH

39
Q

Once FSH/LH are secreted b/w weeks 10-12 in utero; what happens to their levels?

A

they remain low until puberty

40
Q

Before puberty, which hormone level is higher, FSH or LH? How does this change at during the adult reproductive period? What about in old age?

A

before puberty–> FSH > LH

at puberty–> LH>FSH

old age–> FSH>LH

41
Q

When is FSH greater than LH in the female?

A

during childhood and elderly years

42
Q

When is LH greater than FSH in females?

A

during puberty and reproductive years

43
Q

What happens to FSH and LH levels during puberty?

A

they rise and become pulsatile (assoc. with female 28 day menstrual cycle)

44
Q

What is the primary hormonal event that is initiated at puberty? What will this drive secretion of? What will that cause?

A

initiated of pulsatile secretion of GnRH –> which drives parallel secretion of FSH and LH –> therefore stimulate gonads to produce hormones

  • testosterone in males
  • estradiol in females
45
Q

What is required for normal reproductive function?*

A

pulsatility

46
Q

When do large pulses of LH occur during puberty?

A

nocturnal

47
Q

What will GnRH up regulate? What will this cause?

A

its own anterior pituitary receptor

causes increase sensitivity of GnRH receptor in anterior pituitary

48
Q

What drive secretion of FSH and LH?

A

GnRH

49
Q

What is responsible for secondary sexual characteristics that appear during puberty?

A

increase circulating levels of sex steroids

50
Q

What may delay onset of puberty?

A

Extreme stress or caloric deprivation

CNS and nutritional status may play a role

51
Q

What effect will a decrease in melatonin have on onset of puberty?

A

it inhibits GnRH–> therefore a decrease in melatonin will cause an increase in GnRH–> causing puberty to occur earlier

52
Q

When are melatonin levels highest in our life? when are they lowest?

A

highest–> during childhood and adulthood

lowest–> during puberty

53
Q

What will removal of the pineal gland in a baby cause?

A

earlier onset of puberty (due to no melatonin produced to inhibit GnRH)

54
Q

Do males or females tend to develop secondary sex characteristics sooner?

A

females

55
Q

At what ages will we see the following in boys:

  1. pubic hair
  2. penile growth
  3. growth spurt
A
  1. 12-16 yrs
  2. 13-15 yrs
  3. 13-16 yrs
56
Q

At what ages will we see the following in girls:

  1. breast development
  2. pubic hair
  3. menarche
  4. growth spurt
A
  1. 11-15 yrs
  2. 9-15 yrs
  3. 10-16 yrs
  4. 11-14 yrs
57
Q

What will Leydig cell proliferation increase synthesis and secretion of?

A

testosterone

58
Q

What is the growth of testes primarily due to? What does this initiate?

A

increase number of seminiferous tubules–> initiation of spermatogenesis

59
Q

Does growth spurt and closure of epiphyseal plates begin and end earlier in males or females?

A

females

60
Q

What does pubic/axillary hair growth proceed? What is it depend on?

A

proceeds menarche

dependent on increase secretion of adrenal androgens

61
Q

What will activation of hypothalamic-pituitary axis in females drive? When is the first sign of budding of breasts?

A

synthesis of estradiol by ovaries

following w/in 2 years of menarche

62
Q

What is the major androgenic hormone?

A

testosterone

63
Q

The biochemical pathway for testosterone is similar to adrenal cortex, but what are the important differences?

A
  1. testes LACK 21 beta-hydroxylase and 11beta-hydroylase

2. testes HAVE additional enzyme 17beta-hydroxysteroid dehydrogenase

64
Q

What additional enzyme do the testes have that the adrenal cortex does not? What does this enzyme do?

A

17beta-hydroxysteroid dehydrogenase

converts Androsternedione into Testosterone

65
Q

What converts Testosterone into Dihydrotestosterone (DHT)? Where does this occur?

A

5alpha-reductase

at the target tissues

66
Q

Is testosterone active in all androgenic target tissues?

A

no

at some tissues testoserone is converted into dihydrotestosterone by enzyme 5alpha-reductase

67
Q

What percentage of circulating testosterone is bound to plasma proteins? What are those plasma proteins?

A

98%

Sex steroid-binding globulin (SSBG) and albumin

68
Q

What form of circulating testosterone is biologically active?*

A

FREE

69
Q

What functiosn as a reservoir for the circulating testosterone hormone?

A

SSBG (Sex steroid-binding globulin)

70
Q

What is SSBG (Sex steroid-binding globulin) stimulated by? What is it inhibited by?

A

+ by estrogens

  • by androgens (like neg. feedback)
71
Q

What controls both functions of the testes?

A

Hypothalamic- pituitary axis (HPA)
Controls:
- FSH
- LH

72
Q

What does FSH stimulate in the testes?

What does LH stimulate in the testes?

A

spermatogenesis and sertoli cell fxn

secretion of testosterone

73
Q

What two negative feedback paths is HPA (Hypothalamic- pituitary axis) controlled by?

A
  1. testosterone INHIBITS both ant. pit. LH and hypothalamic GnRH secretion
  2. Sertoli cells secrete glycoprotein called INHIBIN –> that inhibits ant. pit. FSH secretion
74
Q

What type of effect does testosterone have on the sertoli cells? Release of what is stimulated?

A

paracrine effect on them to stimulate release of inhibin

75
Q

What is mediated by Testosterone?

A
  • differentiation of epidiymis, vas deferens, seminal vesicles
  • increase muscle mass
  • pubertal growth spurt
  • epiphyseal closure
  • growth of penis and seminal vesicles
  • deepening of voice
  • spermatogenesis
  • neg. feedback on Ant. Pit.
  • libido
76
Q

What is mediated by Dihydrotestosterone (DHT)?

A
  • differentiation of penis, scrotum, and prostate
  • male hair pattern
  • sebaceous gland activity
  • growth of prostate
77
Q

What will the use of 5alpha-reductase inhibitors cause?

A

block conversion of testosterone to dihydrotestosterone

  • block production of active androgens in some targets

Ex: finasteride–> used to Tx benign prostatic hyperplasia and male pattern baldness

78
Q

What is used to Tx benign prostatic hyperplasia and male pattern baldness?

A

a 5alpha-reductase inhibitor called Finasteride

79
Q

What will someone who lacks 5alpha-reductase result in, but has testes that secrete testosterone?

A

no dihydrotestosterone (DHT):

Therefore no:
- external male reproductive parts–> penis, scrotum, prostate

  • in fetus; testes synthesized antimullerian hormone which suppressed mullerian ducts–> so no female reproductive tract; BUT had wolffian ducts differentiation and get internal male reproductive tract

Endocrinology -- Freedman (14 decks)

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