Session 3 - puberty Flashcards
what is puberty
A stage of human development when sexual maturation and growth are
completed and result in ability to reproduce
– Morphological physiological and behavioural development and development of secondary sexual characteristics
why can a tumour in the pineal gland cause early onset of puberty (pernicous puberty)
ANSWER LATER
what is the current average age of menarche
13 years
what is thought to be the critical weight that girls have to reach before starting their periods
47kg
periods can stop if you ball below this
body weight is thought to be the most important factors
leptins may be involved in signalling to show that there is enough fatty deposits to sustain another life
both boys and girls have oestrogen and testosterone
what keeps free testosterone levels lower in girls
testosterone binding proteins
and what age do girls commence puberty
9-13 years
- breast bud development (thelarche)
- pubic hair growth (adrenarche)
what causes the growth of pubic hair in males and females
response to testosterone
what is thelarche
is the onset of female breast development
what is adrenarche
when the adrenal cortex secretes increased levels of androgens such as DHEA and DHEAS, but without increased cortisol levels.
causes pubic hair growth, onset of growth spurt and onset of mestrual cycles (menarche)
what is the role of oestrogen in a growth spurt
Oestrogen important in maintaining bone mass and
closing epiphysial growth plates in males and females.
Females enter and leave the growth spurt face earlier so tend to be shorter
what is aromatase
an enzyme found in fatty tissues that converts testosterone to oestrogen
at what age do boys go through puberty
10-14
what happens to boys during puberty
pubic hair growth
spermatogenesis
growth spurt
genital development (testosterone)
what is a growth spurt
accelerated somatic growth which occurs in both boys and girls
it depends on growth hormone and sex steroids in both sexes
earlier and shorter in girls
men larger becaucse growth spurt longer and slightly faster
ended in both sexes by epiphyseal fusion
oestrogen causes the epiphyses to close earlier in girls
what causes the onset of puberty
Hormonal changes precede physical changes
Increased stimulation of hypothalamo-pituitary-gonadal axis
– gradual activation of the GnRH
– increases frequency and amplitude of LH pulses.
– gonadotropins stimulate secretion of sexual steroids
(oestrogenes and androgenes)
– extragonadal hormonal changes (elevation of IGF-I, and adrenal steroids)