Physiology of Puberty Flashcards

1
Q

Puberty:

A
  • stage of physical maturation in
    which an individual becomes
    physiologically capable of pro-
    creation
  • transition from childhood to
    reproductive maturity
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2
Q

Onset of Puberty:

A
  • 8-13 in girls
  • 9-14 in boys
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3
Q

Physical changes in puberty:

A
  • growth spurt
  • secondary sex characteristics:
    pubic & axillary hair, breasts, male
    voice changes
  • menarche/spermatogenesis
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4
Q

What are growth spurts?

A

short periods of time when child experiences quick physical growth in height and weight

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5
Q

Growth Spurt: Signs:

A
  • increased appetite: child’s
    nutritional needs increase before
    and during growth spurt
  • increase in bone and muscle
    growth
  • increase in amount of fat stored in
    the body
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6
Q

Chronological Order of Puberty: Girls:

A
  • growth spurt
  • thelarche: breast development
  • pubarche: pubic hair
  • adrenarche: axillary hair
  • menarche: menstruation

*not always true

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7
Q

Chronological Order of Puberty: Boys:

A
  • testicular enlargement
  • penile length increases
  • pubic hair
  • growth spurt
  • axillary and facial hair
  • deep voice
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8
Q

Which scale is used to describe the onset and progression of pubertal changes?

A

The Tanner Stages

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9
Q

Tanner Stages: Difference between how girls and boys are rated?

A
  • boys are rated for genital
    development and pubic hair
    growth
  • girls are rated for breast
    development and pubic hair
    growth
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10
Q

Tanner Stages: Girl’s Breast Development:

A

insert slide

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11
Q

Tanner Stages of Male External Genitalia:

A

insert slide

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12
Q

Tanner Stages: Pubic Hair Growth:

A
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13
Q

What is minipuberty?

A
  • HPG axis is active in utero
  • and first six months in boys
  • first 2 years in girls
  • **quiescent until the onset of
    puberty
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14
Q

HPG Axis:

A
  • at onset of puberty
  • hypothalamus starts to produce
    pulsatile secretion of
    gonadotrophin-releasing hormone
    (GnRH)
  • stimulates the pulsatile release of
    FSH and LH from the anterior
    pituitary

insert diagram

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15
Q

Role of Hormones in HPG Axis:

A

insert diagram

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16
Q

Role of Testosterone in Puberty:

A
  • increased muscle mass
  • penile growth
  • deepened voice
  • pubic hair growth
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17
Q

Role of LH in Puberty:

A
  • stimulates testosterone production
  • from interstitial cells of testes
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18
Q

Role of FSH in Puberty:

A
  • stimulates testicular growth
  • enhances production of an
    androgen-binding protein
  • by Sertoli cells, which are a
    component of the testicular tubule
    necessary for sustaining sperm cell
    maturation
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19
Q

Puberty: Extra-Gonadal Hormonal Changes:

A
  • increased adrenal steroid
    (androgen) from adrenal cortex
  • involved in secondary sexual
    characteristics and growth of sex
    accessory structures eg prostate
  • increased GH secretion from
    anterior pituitary increases
    elevation of insulin like growth
    factor -> increased growth
  • increased TSH secretion from
    anterior pituitary in both sexes
  • increases metabolic rate and
    promotes tissue growth
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20
Q

What categories of factors affect the timing of puberty?

A
  • genetic
  • environmental
  • neuroendocrine
21
Q

What environmental factors can affect the timing of puberty?

A
  • nutritional status
  • chronic illness
  • migration
  • frequent infectious disease
  • pollution
22
Q

Timing of Puberty: Neuroendocrine Factors:

A
  • neuroregulation of puberty vis
    neuropetides: kisspeptin,
    neurokinin B and dynorphin A
  • at onset of puberty, stimulatory
    drive of neurokinin B increases
  • results in kisspeptin production
  • which regulates GnRH hormones
23
Q

Precocious Puberty: Ages:

A
  • girls: <8yrs
  • boys: <9 yrs
24
Q

Delayed Puberty: Ages:

A
  • girls: >13 yrs
  • boys: >14 yrs
25
Q

Precocious Puberty:

A
  • early/premature puberty
  • presence of true pubertal features
    at a young and inappropriate age
  • either central/true precocious
    puberty or peripheral/pseudo-
    precocious puberty
26
Q

Central/True Precocious Puberty:
- overview (3)
- causes (4)

A
  • gonadotrophin dependent
  • under 8 in girls, under 8 in boys
  • premature activation of HPG axis

Causes:
- brain tumours
- raised intracranial pressure
- CNS malformation
- mutations of the kisspeptin
receptor hence dysregulation of
GnRH neurones

27
Q

Central Precocious Puberty: Characteristics:

A
  • secondary sexual characteristics
    develop too early but not true
    puberty
  • premature thelarche
  • premature adrenarche/pubarche
28
Q

Peripheral Precocious Puberty:
- overview
- causes

A
  • gonadotrophin independent
  • girls <8yrs, boys <9yrs

Causes:
- ingestion of sex steroids
- hormone-producing tumours
(ovaries/testes)
- adrenal gland abnormalities ->
congenital adrenal hyperplasia
causing overproduction of sex
hormones

29
Q

Precocious Puberty: Management:

A
  • goals of managing precocious
    puberty are to treat the underlying
    cause and block
    production/response of excess
    hormones
  • refer to endocrinologist to prevent
    complications
  • baseline measurement of
    hormones: LH, FSH, Testosterone,
    GnRH
  • follow up
30
Q

Precocious Puberty: Treatment:

A
  • GnRH agonists halt the physical
    progress of puberty
  • produce initial increase in sex
    hormones
  • continued non-pulsatile
    stimulation
  • LH and FSG synthesis inhibited
  • oestrogen and testosterone levels
    decline
  • GnRH antagonist blocks the
    gonadotrophin receptors in the
    pituitary
  • inhibit LH and FSH release directly
  • lacks the initial surge typical of
    GnRH agonists
  • treatment helps in very young
    children with central precocious
    puberty
31
Q

Delayed/Late Puberty: Overview:

A
  • more common in boys than girls
  • most are not pathological
  • family history common
  • girls: >13yrs
  • boys: >14yrs
32
Q

Delayed Puberty: Causes:

A
  • chronic illness: kidney
    disease***search
  • malnutrition -> eating
    disorder/coeliac disease
  • problem with ovaries, testes,
    thyroid, pituitary
  • genetic conditions: Turner
    Syndrome, Klinefelter Syndrome
33
Q

Delayed Puberty: Peripheral Defects:

A
  • hypergonadotrophic
    hypogonadism or primary
    hypogonadism
  • disorder of abnormal gonadal
    function with decreased
    testosterone in males and
    oestradiol in females -> delayed
    sexual development
34
Q

Peripheral Defects: Hypergonadotrophic hypogonadism/primary hypogonadism: Causes:

A
  • turner’s syndrome
  • post-malignancy
    chemo/radiotherapy
  • surgery can cause gonadal failure
  • polyglandular autoimmune
    syndromes
35
Q

Turner Syndrome:

A
  • female only genetic disorder
  • 1 in every 1 in 2000 babies
  • only one normal X sex
    chromosome not two
  • 45X (45 chromosomes instead of
    46)
  • primary and secondary female sex
    characteristics are not fully
    developed
  • short stature, webbed neck, widely
    spaced nipples, shield like thorax
36
Q

Turner Syndrome: Treatment:

A
  • growth and sex hormone
    substitution
37
Q

Turner Syndrome:

A

insert diagram

38
Q

Delayed Puberty: Central Defects:

A
  • congenital hypogonadotrophic
    hypogonadism
  • due to a problem with the pituitary
    gland or hypothalamus
  • decreased LH and FSH
  • hence gonad will not be able to
    produce sex hormones

Causes:
- hypothalamic lesions can lead to
low GnRH
- rare genetic mutations inactivating
FSH/LH or their receptors

39
Q

Delayed Puberty: Central Defects: Diagnosis:

A
  • low gonadotrophin levels
  • poor response to stimulation with
    GnRH stimulation test
    **test checks how well the
    pituitary gland works
  • imaging can help
40
Q

Delayed Puberty: Treatment Overview:

A
  • treat underlying cause
  • use meds short term to increase
    hormone levels and trigger the
    start of puberty
  • hormone replacement therapy
41
Q

Klinefelter Syndrome:

A
  • mostly boys and men
  • normal puberty and find out only
    in adulthood..delayed puberty is
    possible
  • 47XXY
  • karyotype shows extra
    chromosome
  • learning difficulties

Teenagers:
- taller than expected
- long limbs
- broad hips
- poor muscle tone and slow muscle
growth
- reduced facial and body hair
- hair grows later than usual
- small penis and testicles

42
Q

Klinefelter Syndrome:

A

insert diagram

43
Q

Klinefelter Syndrome: Treatment:

A

Testosterone Replacement Therapy

44
Q

General Investigation for Children with Pubertal Issues:

A
  • Bloods: LH, FSH, thyroid and
    growth hormones -> provide
    current situation not future
  • Thyroid stimulates production of
    growth factors and GH production
  • physical examination will inform
    about puberty status
  • children within the normal range
    for height and development are
    not likely to have a medical
    problem
  • hand x-ray to determine likely
    adult height
  • ultrasound or MRI to check for
    tumours
45
Q

In terms of chronological order of puberty in boys, what is the first change?

  • pubic hair
  • axillary hair
  • breast development
  • testicular enlargement
A

testicular enlargement

46
Q

“Papilla is elevated above the level of the chest wall.”

As per Tanner stages of girls breast development:

  • stage 1
  • stage 2
  • stage 3
  • stage 4
A

Stage 1

47
Q

Early or Precocious puberty in girls occur in ages less than:

  • 8
  • 9
  • 10
  • 11
A

8 years old

48
Q

What is the chromosome number in Turner Syndrome?

  • 46XY
  • 45Y
  • 45X
  • 47XXY
A
  • 45X
49
Q

What chromosome number in Klinefelter Syndrome?

  • 46XY
  • 45Y
  • 45X
  • 47XXY
A
  • 47XXY