Puberty Flashcards
(19 cards)
describe leptin role in puberty
leptin is a peptide hormone which is produced from fat cells (adipocytes), they hypothalamus has receptors for leptin, this acts as an inhibitor for puberty as GnRH is secreted from the hypothalamus.
what is the diffrence between male and felame hypothalamus and how does it occure prenatal?
both have a tonic centre but males do not have a surge centre. this is caused by estradiol which is transported to the brain during embryogenesis.
in females alpha - fetoprotein binds to the estradiol preventing it from impacting the brain.
in males their is not alphs - fetoprotein which means it goes into the brain and shrink the surge center untill it is depleted.
define puberty
process which allows reproduction to successfully occur.
when does the depetion of the surges center occur in embryogenesis?
when the testes devlop the testosterone inc vonerted to estradiol which crosses the blood brain barrier, depleting the surge center.
how is puberties onset limited and what are the factors?
ability of presynaptic neurons to transmit information of GnRH, so secretions can increase. These neurons can be influenced by: nutrition, exposure to environmental/ social cures and genetics.
list the variation of criteria for female puberty
age of:
estrus, ovulation, pregancy
list the variation of criteria for male puberty
Age of:
behavoural traits,
ejaculation,
spermatozoa first develop in ejaculate,
spermatazoa appear in urine,
threshold number of spermatazoa is reached in ejaculate
describe how puberty in females is characterized
- enough estradoil produces to stimulate GnRH to trigger ovulation
- threshold in the tonic center to stimulate GnRH is decreased
desribe the diffrence feedback loop in the tonic centre and the surge centre
tonic centre = negative feedback loop (constant pulse which begins when the estradiol threshold is loweredat the start of puberty
surge centre = positive feedback loop (ovulation is triggered by rush of GnRH which release is triggered when threshold of estradiol is reached (only when dominate follicule from ovaries produces it)
Puberty in males is characterised as
Negative feedback loop decreases the hypothalamus sensitivity to testosterone/estradiol which stimulate GnRH, which means the body increases GnRH production (increasing LH and FSH exponentially) until puberty occurs.
was is the threshold body size?
the animal maturity or ‘fatness’ needed to be reached before puberty can occur. Metabolic signals affect the production of GnRH, thus a level of ‘fatness’ is required.
what is the evolutionary purpose of the threshold body size
during pregnancy the animals energy is heavily diverted to the fetus and as such puberty is reached once the animal has accomplished in personal growth so that the mother can divert he energy to the fetus without dying.
what are some of the biochemial indicators for the threshold body size
glucose and fatty acid in the blood, was proven that low level interup estrus
describe leptin role in puberty
Leptin hormone peptide that is produced from adipocytes (fat cells). Receptors for this hormone are found throughout the body, most importantly on the hypothalamus, which strongly indicates that it plays a role in GnRH inhibition.
list possibel enviromental/ socail cues that effect onset of puberty
season of birth, photoperiod, presence/ absence of opposite sex, density of group (same sex)
how does the season of birth effect heirfers puberty onset
spring/ summer weather tend to hasten puberty.
how does the photoperiod effect the sheep pubery onset
Puberty for sheep occurs after a photoperiod during September is reached, thus fall born lambs require twice as long to reach puberty than spring lambs.
how does the presence of the opposite sex during the peripubertal period effect puberty onset
Pheromonal influence from the males can induce puberty early (evolutionary this is to ensure opportunal pregnancy)
how does the density of same sex groups effect the pubert onset (swine)
Glits in small groups have delayed puberty (ten or less)
