Puberty Flashcards
What is normal puberty?
It is when the secondary sex characteristics appear and mature. Growth spurt and fertility is achieved.
All happens in the correct order.
Central activation of the H-P-gonadal axis
Stimulation of the sex organs and secretion of the sex steroids.
Progressive sequential changes
Apropriate rate.
Girls: first sign is breast development (age 9.5-10.5) then growth spurt (menarche occurs 2 years after breast development)
Puberty is early at age 8.
Males: increased testicular development, growth spurt later
males going to puberty later (11.5)
When are the three puberties?
In fetal development, at around 2 months and in the teens.
What is thelarchie and pubarche?
Breast development
Pubic hair development
What is gonadarche, menarche and gynaecomastia?
Gonadal development, first menstrual period and breast development in boys
How do you look at puberty in males and females?
Testicular volume (>3 ml = puberty), stretched penile length and breast development.
Need to look at hair and genital development and comparing to a chart
How does LH and FSH production change during puberty?
Early puberty? tonic phase increases and night pulses begin
Mid-puberty - greater increase in tonic phase and higher amplitude night pulses
Late puberty
Day and night pulses.
How does the axis change from fetal, childhood to puberty?
Fetal: Gonadostat is off. Hypothalamus is stimulating pituitary with GnRH and the pituitary is producing LH and FSH which act on the gonads to produce estrogen and testosterone. Little negative feedback.
This is inhibited in childhood as the gonadosat is turned on.
Negative feedback of testosterone and estrogen act on the hypothalamus.
In puberty it returns to the first type.
What happens in the transition to puberty?
Gonadostat is off. Increased pulsatile GnRH and LH/FSH production.
Increased sex steroid production and reduced sensitivity to negative feedback.
What is the gonadostat?
GABA is a part of it.
Kisspeptin also has a role in starting the process.
What is inhibin?
Stimulated by FSH -> negative feedback to FSH secretion. Produced by sertoli cells (m) and granulosa cells (f)
What is adrenache?
When the adrenal glands wake up to produce androgen production.
Adrenal androgens lead to pubic hair in girls but this is not a sign of puberty.
What is leptin?
An adipostatic hormone that is increased when the fat mass is increased. May indicate the timing of puberty which is why obese children enter puberty earlier.
obese -> leptin increase -> puberty
Starvation -> delay of puberty
Body composition and puberty?
Prepubertal - similar lean, skeletal and fat mass to girls.
Puberty: lean mass, skeletal mass is 1.5 x greater for males and fat mass is 2x greater in females.
Fat in males is truncal, for females it is generalized
Increased bone mass density in puberty. Peak bone mass is after puberty due to sex steroids.
What are the pubertal growth factors?
Increased sex steroids
Increased growth hormone
Increases IGF-I
Increased insulin
What is central precocious puberty and how do you test to see if puberty is occurring?
Early stimulation of GnRH - do a GnRH stimulation test. If not in puberty then should not respond strongly to GnRH (FSH/LH levels).
A estrogen secreting tumour would cause breast development but the GnRH stimulation test would not work.
