Puberty Flashcards
Adrenarche
Activation of adrenal cortex for the production of adrenal androgens, and typically occurs before the onset of puberty. Leads to pubarche (pubic and axillary hair growth) and doesn’t require gonads.
Gonadarche
Activation of the gonads by the pituitary hormones FSH and LH and sex steroid secretion. Leads to thelarche (breast dev) and sexual maturation. Does not require the adrenal gland
Menarche
Age of onset of first menstural period
Where is DHEAS produced?
During andrenarche, the adrenal gland’s zona reticularis produces DHEAS
Is adrenarche under direct control of ACTH/cortisol?
NO, has nothing to do with the gonads
What stimulates gonadarche
Onset of GnRH pulsitility
What usually comes first, thelarche or pubarche?
Thelarche, though in 8-15% of girls, pubarche occurs first
What causes breast dev?
Estrogen production by ovaries
Breast Tanner stage I
Prepubertal
Breast Tanner stage II
Breast bud forms, areola erect (11.2 y.o)
Breast Tanner stage III
Breast tissue enlarges beyond areola (12.2)
Breast Tanner stage IV
Areola and papilla form second mound (13.1y.o)
Breast Tanner stage V
Adult breast: areola and breast tissue same plane, papilla erect (15.3 y.o)
Limitations to Tanner staging
- Based off of limited pop
- Dif ethnicities=dif ages
(note seq of events is the same)
Normal breast dev occurs at a younger age in…
African Americans than in Whites
What age range of breast dev req further evaluation of any girl?
Dev at age 13
Which enzymes initiate adrenarche
P450c17 which inc DHEA, DHEA-s, androstenedione
How many years before the appearance of secondary sex charac does adrenarche occur?
2
What is adrenarche responsible for
Pubarche
Does andrenarche play a role in skeletal growth?
Not really
What is the relationship between adrenarche and gonadarche?
They are temporally related, but independent, functionally unrelated biologic events
F. Pubic Tanner stage I
Pre pubertal, no pubic hair
F. Pubic Tanner stage II
Coarse, curly, pigmented hair laterally (11.7)
F. Pubic Tanner stage III
Coarse, curly hair spread across pubis (12)
F. Pubic Tanner stage IV
Abundant adult pubic hair, limited to pubis (13)
F. Pubic Tanner stage V
Pubic hair present on medial thigh (14)
What race does pubarche usually occur in first
African American ealier than white
When does menarche occur?
Once there is sufficient gonadal estrogen, secretion occurs and the endometrial proliferation occurs. First period is not necessarily associated with ovulation. Postmenarcheal cycles are initially anovulatory. Sustained predictable LH surge responses to estradiol with ovulation are late pubertal events. Can be anovulatory for even 5 years.
How long after breast dev does menarche occur
approx 2 years
Why do we think age at menarche is dec?
Better nutritional status, improved standards of living
M. Pubic Tanner I
Preadolescent (Testis and Penis)
M. Pubic Tanner II
P: slight enlargement, T: enlarged scrotum, pink, texture rough
M. Pubic Tanner III
P: inc length
T: inc size
M. Pubic Tanner IV
P: Glans enlarged, inc breadth
T: enlarged darker color
M. Pubic Tanner V
Adult size (P and T)
At what age and tanner stage does spermatogenesis first start?
11-15 y.o, Tanner 2-3
What is the mean age of first conscious ejaculation?
13.5
Growth spurt dep on what hormone?
IGF-1 and sex sterioids
What initially causes long bone growth in girls
Estrogen
Descibe changes in genitalia in girls
- Vag length increases
- Labia become thick and rugated (minora first)
- Adipose tissue appears in mons pubis
- clit enlarges
- Vag mucosa becomes less shiny and thicker
Describe chanegs in genitalia boys
- Testes inc in size
- Sertoli cells stop mitosis
- Germ cells predominate
- Leydig cells develop
- Spermatogenesis occurs
- Penis enlarges
- Ejac occurs
How many years after girls is boys growth spurt
About 2 years
Describe gonadotropin levels in the neonatal pd
- High after birth up to 2 years
- Release of suppression from maternal E and P when born and umbil cord clamped
- Transient E or T sec induced by high FSH/LH at this time leading to dev of ovarian cysts in females
Describe gonadotropin levels in childhood
- FSH, LH levels suppressed
- E and T suppressed
- Low level pulses of GnRH (not due to neg feedback since that is suppressed)
What initiates puberty
Pulsatile GnRH is responsible for gonadarche
Evidence: pit and gonads dont limit gonadarche, GnRH can stim puberty
What is happening to follicles in childhood
Dev but only to antral stage (pre-gonadotropin dep stage)
Why is LH a marker for GnRH but FSH is not?
LH has a shorter half life so its levels mirror GnRH pulsatility
Describe LH in males during puberty
Initial sign of puberty is high LH pulse at night
Mid-puberty
is when sufficent gondal estrogen is secreted to proliferate endometrium and allow menarche
How long are cycles usually anovulatory for
First 1-2 years
What is the first gross sign of pub in males
Growth of testes
The inhibition on the hypothalamus during childhood is…
intrinsic, agonadal children have same FSH/LH suppression pre puberty
List some factors that may influence the onset of puberty/turn on hypothal
- Genetic (sisters and mom have similar age of onset)
- Environment (less phys activity, better nut, urban environment)
- epitgenetics (
- Toxic exposure (BPH)
- Nutritional status (fat can produce estrogen, delayed in malnurished)
- Hormonal factors (in meats
What are some theories as to what triggers release on GnRH after childhood?
- GABA is inhibiting GnRH in female via a GnRH receptor
- NPY: inhibits GnRH in males via hypothal receptor
- Leptin: Receptors on hyppothal and ant pit, inc during childhood until puberty. Necessary in a permissive role for gonadarche to occur.
- Kisspeptin:
What is the leading theory today?
Kisspeptin: Inc just before pub, may come together with estrogen to stimulate GnRH release and begin puberty
