Sept14 A1-Puberty Flashcards
puberty def
age where indiv becomes sexually mature and capable of reproducing
in the female, imp reason for delay of puberty
majority of the 7M oogonia are killed before puberty (active destruction of dangerous eggs)
hormonal changes in puberty
testo, E, P rise a lot (previously very low.). same for GnRH, FSH, LH
major switch for puberty
kisspeptin. acts on adult brain GnRH
output effector functions of the hypothalamus
3 main are
- endocrine
- autonomic
- behaviour
- all three form appetite*
why is it true that girl and boys who go into puberty later end up taller
because puberty is driven by food supply and anxiety
when pituitary starts pulsating in women
- at age 6-8, LH pulsatility at night only
- follicles start to dev but die after 2 missed pulses. (this leads to cyst formation in the ovaries)
- allows skeletal maturity to occur without fertility
when pituitary starts pulsating in men
-at age 6-8, GH pulsatility at night only
what happens when puberty starts
- the kisspeptin neurons decide that the pulses will last 24 hours
- get menarche (first menstrual cycle) in women
- men become fertile from the time they have their first sperm
why does testo not do HP feedback in the female
it is aromatized to estradiol in the H and P
3 blips of FSH and LH in life
- fetal life (gender establishment)
- late enfancy (baby dimorphism and changes)
- puberty
- at menopause, in women, FSH and LH go very high and stay high for rest of life*
why puberty (ctly high FSH and LH) eventually happens in life
because at each FSH and LH blip (first two), pituitary loses sensitivty to estrogen feedback (inhibiting FSH secretion) so need more and more for it to happen
at same time, GnRH secretion + sensitivity increases and gonadal response increases
most important thing to drive puberty
food
- food store is signaled by leptin
- food intake is signaled by insulin
other drives to puberty
hypothalamus, pituitary and gonadal
hypothalamic drive to puberty
- kisspeptin stimulates it
- MKRN3 and opioids inhibit it
