Adolescence (W3 KPH) Flashcards
define puberty
stage of physical maturation in which an individual becomes physiologically capable of sexual reproduction
what is puberty characterised by?
appearance of secondary sexual characteristics
pubertal growth spurt resulting in final adult height
physiological, cognitive and social changes
what does kisspeptin do?
stimulates GnRH secretion in the hypothalamus during the onset of puberty
what are the first signs of puberty?
M - testicular enlargement
F - breast development
what are the secondary signs of puberty?
axillary hair
body odour
pubic hair
acne
growth spurt
body composition changes
facial hair growth (M)
menstrual cycle beginning (F)
what is tanner staging?
a stating system of 5 stages
stage 1 - pre-pubescent
stage 5 - adult
in M - genitals and pubic hair growth
in F - breast and pubic hair growth
what is precocious puberty?
puberty occuring at an usually early age
in M - below 9
in F - below 8
what is delayed puberty?
when a person lacks or has incomplete development of specific sexual characteristics past the usual age of puberty onset
in M - 14
in F - 13
what are the gonadotropin dependant causes of precocious puberty?
hypothalamus/pituitary tumour
cerebral malformations
CNS injuries
idiopathic
genetic
what are the gonadotropin independent causes of precocious puberty?
gonad/liver tumour
adrenal gland hyperplasia (CAH)
exogenous androgenic or oestrogenic steroids
genetic
what are some of the basic investigations for precocious puberty?
gonadotropin blood test
sex steroids
bone age
what are the main reasons for delayed puberty?
hypergonadotropic hypogonadism
hypogonadotropic hypogonadism
constitutional delay of growth
what are the general investigations for delayed puberty?
visual field exam (tumours)
dysmorphic features
height/weight
family history
where is kisspeptin found?
hypothalamus:
AVPV nucleus and ARC nucleus
what does kisspeptin act with and how does it function?
kisspeptin (+) acts with GABA (-) to initiate reproductive development, induce puberty and regulate the HPG axis
describe what happens to kisspeptin during puberty
KiSS1 neurons increase in the AVPV of the hypothalamus
number of neurons that contact GnRH increases
increase is larger in the female reproductive tract
describe the secretion style of kisspeptin
pulsatile style every 60 mins during puberty
correlates with GABA pulses
explain the role of leptin in puberty
leptin is released from adipose tissue when a certain body weight and body fat composition is reached
leptin stimulates increase in kisspeptin molecules
what can mutations in kisspeptin cause?
precocious puberty
delayed puberty (idiopathic hypogonadotropic hypogonadism)
what do GnRH pulses stimulate?
LH and FSH in the anterior pituitary