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Endo/Repro Block2 > Puberty > Flashcards

Puberty Flashcards

1
Q

what is puberty?

What external features are present/?

A

final stage of maturation of HPG axis

External: 2’ sex characteristics appear & growth spurt–> striking sexual dimorphism to mature fertil adults

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2
Q

What is the mini-puberty of infancy?

When does it hapen?

A

Mini-puberty: 6-8wks

  • HPG axis becomes active
    • sex steroid levels comparable to those seen in early/mid puberty but w/o external effects
    • biological relevance is unkown
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3
Q

What is happening in pre-puberty state?

How do children enter puberty?

A

long period from mini-puberty to puberty where HPG axis is suppressed

**if this suppression is taken away= HPGa is reactivated–>child enters puberty

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4
Q

What are 5 of the major changes in puberty/HPGaxis?

A
  1. ^^activity of adrenal glands–>produce steroids
  2. ^^ pulsatile GnRH & FSH/LH secretion
  3. corresponding ^^ in circulating estrogen [females] & test [males]
  4. mitosis of 1’ spermatogonia [no oogonia changes]
  5. correlated w/ onset of gamete maturation
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5
Q

What hormonal pulses activate steroid prodxn in gonads?

A

pulsatile GnRH–> Lh surges–> gonad steroid prodxn

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6
Q

What phenotypic changes occur in puberty?

A
  • axial growth
  • growth of 2’ sex organs
  • gender & nongender specific hair growth
  • central processing alterations due to central pathway remodeling
    • prioritizing pathways which have developed and removal of those that havent
    • impaired judgement
  • vocal cord thickening
  • menarche
  • libido
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7
Q

What are the 4 stages of sexual changes [similar to Tanner staging]?

A

Adrenarche: adrenal zona reticularis development–> ^^androstenedione & DHEA prodxn–> pubic hair growth

Thelarche: breast development due to ^^ estrogens

Gonadarche: prodxn of ovarian H’s & mature gametes

Menarche: uterine responses to ovarian H’s

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8
Q

What are the Tanner stages of sexual maturity for boys?

A
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9
Q

What are the Tanner stages of sexual maturity in females?

A
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10
Q

What are the tanner stages of sexual maturity of both boys & girl [general]?

A
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11
Q

When do girls start breast development, menarche, and complete puberty on avg?

When do girls usually reach peak height velocity?

Which ethnicity tends to start puberty earlier?

A

Breast development avg: 10 yo

Peak Height velocity: 11 yo

Menarche: 12 yo

Completes puberty: 14yo

African Am girls tend to start puberty earlier

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12
Q

When do most boys begin pubertal changes?

When do they reach peak height velocity?

When do they reach strength spurt?

When do they complete puberty?

[all on averages]

A

pubertal changes begin: 11-12 yo

Peak height velocity: 13-14

Completion of puberty: 15yo

Strength spurt: 15.5yo

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13
Q

What factors can influence age of onset of puberty?

A

genetics, nutrition [BMI & height], others

**^^BMI/height/weight–>earlier onset of puberty [girls esp.]

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14
Q

How has the age of menarche changed over the past 80 years?

A

age of onset has decreased or become earlier

[from 16yo and now down closer to 13]

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15
Q

What are the 2 forms of precocious puberty?

A

gonadotropin dependent & gonadotropin independent precocious puberty

(GDPP & GIPP)

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16
Q

What causes GDPP?

A
  • 80% idiopathic
  • 20% CNS related: hypothalamic hamartomas, CNS tumors, cranial irradiation, hydrocephalus, trauma
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17
Q

What causes GIPP in girls?

in boys?

Both?

A

girls: ovarian cysts or tumors

boys: leydig cell tumors, hCG secreting germ cell tumors [gonads, pineal, liver, retroperitoneum, post. mediastinum,–>all areas of movement prior to coelescence in gonadal ridge]

both: exogenous E= adrenal pathology w/ excess androgen/pit tumors

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18
Q

In general, what will we see in GDPP?

A

early activation of pulsatile activity of HPGaxis [aka CPP] so all puberty signs are stage matched but occur earlier than expected

  • pulsatile GnRH–> ^^LH esp & slightly ^^FSH
  • leads to ^^sex steroid output
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19
Q

What is the main differentiating component of GIPP from GDPP?

What would presence of GDPP w/ adrenarche show?

What about ^^bone age >chronological age w/ adrenarche [boys] & thelarche [girls] mean/show?

A

GIPP exhibits one or two signs of puberty but not all [nnot staged similarly]

  • adrenarche present:
    • tumors of adreanl [rare]
    • CAH–>MC is 21 hydroxylase deficiency
      • ^^DHEA levels & ^^random serum 17OH P
      • most kids have normal DHEA levels though
  • bone age>chrono age:
    • tumors secrete hCG–> binds LH R–>stimulates sex steroid synthesis
    • gonadal tumors–>elevated sex steroids BUT NOT gonadotropins
    • exposure to exogenous sex steroid hormones
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20
Q

How does precocious puberty effect growth/bone growth?

What is the overall effect?

A

PP shows increased levels of E–>converts to estradiol E2

  • prepubertal bone plates are extra sensitive to E2
    • low levels [kid] of E2 favor pubertal growth spurt
    • high levels [adult] cause fusion of epiphysis

**kids with PP are SHORTER than avg **due to early fusion

21
Q

How do we Dx GDPP vs. GIPP?

How do we test for CPP?

Why do we not measure FSH levels?

A
  • GnRH analog stimulation test:
    • ^^Gn induced by test = ** GDPP**
    • normal/not induced Gn levels = GIPP
  • random LH screening test for CPP
    • LH< 0.1 IU/L is prepubertal
    • LH> 0.3 IU/L or more is pubertal
      • random FSH levels dont descriminate b/w PP & pubertal
22
Q

How do we Tx GDPP?

A

Drugs for medical castration

  • GnRH agonists [nonpulsatile] or antagonists
  • anti-E/anti-androgens
  • glucoC’s in the case of CAH
23
Q

What are some major causes of sexual ambiguity?

A

mutations in H prodxn, H R’s, or downstream signaling

Hypogonadism

Sex chromosome loss

Mosaic individuals

24
Q

What is sex [gender] determination dependent on?

A
  • genetic sex: X or Y
  • gonadal sex: initiated in the 2nd month of fetal development
  • phenotypic sex: fetal & pubertal events which dictate phenotype
25
Q

What is the default sex [gender]?

A

Female!!!!

26
Q

Describe 3 steps of female internal sex organ development [1’]?

A
  1. absence of SRY protein = gonadal cortex –>ovary
  2. absence of testosterone = Wolffian ducts degenerate
  3. absence of Mullerian inhibitory Hormone [MIH] = Mullerian duct–>fallopian tube, uterus, & upper vagina
27
Q

Describe 3 steps of internal male sex organ development?

A
  1. SRY protein present = medulla of bipotent gonad–>testis
  2. Anti Mullerian H or MIH present = Mullerian ducts degenerate, leaves Wolffian ducts
  3. Testosterone present = converts Wolffian duct into seminal vesicle, vas deferens, & epididymis
    • DHT controls prostate development seperately
28
Q

In order to become male, what is needed?

When does it start being produced?

What does it do?

A

SRY= sex determining region of the Y chromosome

  • SRY protein is produced by 10 wks
  • binds DNA & upregulates transcription of new genes promoting testes development
29
Q

When does sexual differentiation begin in the embryo/fetus?

A

7 weeks!!!!

30
Q

What/when is the bipotent stage?

A

weeks 1-6 of fetal development when internal repro organs have potential to develop into male OR female structures

31
Q

What 4 substances are absolutely necessary for normal male sex organ development?

what does each do or contribute to?

A
  1. SRY protein aka TDF [testis determining factor]
  2. MIH: inhibits mullerian ducts
  3. Androgens: TESTOSTERONE
    • develops wolffian duct into accessory structures
    • develops external genitalia
  4. DHEA: develops penis & prostate
32
Q

What are external genitalia dependent on?

What would happen if male sex hormones are not present?

A

gonadal sex!!!

External genitalia would be feminized if male sex H’s absent

33
Q

What are all sex steroids derived from?

A

Cholesterol!!!

34
Q

DIt short cut for remembering steroid synthesizing enzyme deficiencies?

A

**1st # is a 1 = **HTN

2nd # is 1= masculinization

11b-hydroxy= HTN &masculin

17a-hydroxy = HTN

21ahydroxy= masculin [HoTN actually]

35
Q

What would cause sex ambiguity in males?

A

46, XY but with low levels of Testosterone:

  • deficiency of Cyp11A = a side chain cleavage enzyme
36
Q

How could virilization of a female child occur? [2 deficiencies]

A

CAH in 46XX

  • 21a-hydroxylase deficiency= ovaries normal
    • ambiguous external genitalia [partial defect]
    • female external genitalia [complete defect]
    • internal structures normal due to no MIH exposure
  • 3B-hydroysteroid DH deficiency = possibly impaired ovaries
    • female genitalia
    • internal structures normoal due to no MIH exposure
    • may go unnoticed until puberty
37
Q

What is androgen insensitivty syndrome? [AIS]

genetics?

who does it affect?

A

AIS= mutations in AR that reduce its signaling capacity [partial or severe]

  • 46, XY cannot or reduced response to androgens
  • X-linked recessive trait
    • phenotypical males are affected most?
38
Q

compare and contrast Complete & incomplete AIS?

A
39
Q

What is 5a-reductase deficiency?

how common is it?

who does it affect?

Tx?

What should you classify the child as if have nearly absent 5a-reductase?

A

RARE

_affects: _ 46, XY: produce testosterone but insufficient conversion to DHT

  • normal internal genitalia [testis]
  • external genitalia [penis & prostate specifically] fail to develop properly = ambiguous female genitalia
    • ​SURPRISE!! female becomes masculinized w/ puberty [if testes left in]

Tx: orchiectomy & E therapy = feminine

nearly absent 5a-reductase= assume female???

40
Q

Virilization of a presumed female child at puberty is due to what?

A

increased testosterone:DHT ratio due to 5a-reductase deficiency

female is actually 46 XY

41
Q

What are 2 sex chromosome anomalies causing sexual ambiguity?

A

XO Turner syndrome

XXY Klinefelter Syndrome

42
Q

Turner syndrome can have which chromosomal variations?

What is this a genetic example of?

What is a common consequence in utero of turners?

A

TURNER’S

  • 46 XX OR 45 XO
    • example of **mosaicism= **sex chromos are doled out unevenly b/w dividing cells
      • earlier in development this happens the more extreme/complete mosaicism is:
        • later= most cells get XX and thus less physical attributes
        • earlier= most cells are XO and results in a female w/ Turners

***similar thing happens with klinefelters syndrome

15% of spontaneous abortions ahve XO karyotype

43
Q

What are the Sx’s/signs of turner syndrome?

A

loss of short arm of one X chromo [usually paternal X]–>gonadal dysgenesis & other abnormalities:

  • neck webbing
  • broad/shield chest
  • horseshoe kidneys
  • CV abnormalities
  • short stature
44
Q

Describe the hormonal effects of Turners syndrome and its effects on sex organ development

A
45
Q

What is Klinefelters syndrome?

What is it a genetic abnormality of?

how many males with these genetic abnormality actually express evidence of disease?

A

Klinefelters is also an example of mosaicism

Klinefelters= 47, XXY

In XXY individuals not all genes on the second X are suppressed/inactivated: some X genes on the psuedoautosomal region correspond to the Y so that triple expression is thought to contribute to the underlying problems

1/500 males carry genotype, but only 1/1000 manifest phenotype

46
Q

Describe the hormonal effects of Klinefelters syndrome and how it affects sex organ development

A
47
Q

Are there only 2 sexes?

What is the best way to determine if an individual is male or female?

A

Scientists now say that sex/gender is on a spectrum!

If you want to know someones sex, the most relevant answer may be to ask him/her!

48
Q
A

Endo/Repro Block2 (11 decks)

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