Puberty Flashcards
week 5
In females, hypothalamic GnRH neurons must develop the ability to respond to _____________ before the can cause sufficient quantities of GnRH to induce ovulation.
estradiol positive feed back
what begins the process of puberty?
GnRH
(Gonadotropin-releasing hormone)
why doesn’t the female hypothalamus become defeminized in they produce estradiol?
estradiol binds to alpha- fetoprotein
What prevents the surge center from forming?
estradiol (E2)
if males don’t produce E2, why doesn’t their surge center develop ?
their testosterone doesn’t bind with alpha fetoprotein which then aromatase into E2
what is the difference in male and female endocrine system after puberty?
male have a steady surge of LH and testosterone every 2-6 hours
females have LH and estradiol surge every 20 days
the onset of puberty in females is
the age at which they can support pregnancy without deleterious effects
the onset of puberty in males is
- behavioral traits are expressed
- first ejaculation
- spermatoza first appears in ejaculation
-ejaculation contains a threshold number of spermatozoa
what are two factors that effect the development of the hypothalamic GnRH neurons in the female?
females must reach a certain body size
certain external or social factors
how do the hypothalamic GnRH neurons acquire the ability to release GnRH in high frequency pulses?
the continued exposure of _____ is required to stop the surge center from working.
androgens
the female hypothalamus contains____ and _____
surge and tonic center
the male hypothalamus has
only the tonic center
what is a surge center?
controls the preovulatory LH surge which triggers ovulation
+ influenced by high concentrations of estrogen
only in females
what is the tonic center?
aka pulse generator of GnRH
controls the frequency of GnRH pulses
what happens if the surge center doesnt function?
ovulation will not occur
what does the LH frequency look like in females?
high amplitudes LH surges once a month and low amplitude pulses in between
what does the LH frequency look like in males?
small pulses of LH that occur every 2-6 hours
why can prepubertal females secrete much GnRH?
estradiol is too low
T/F
GnRH secretion are not sensitive to concentrations of variety of energy-related materials such as glucose/fatty acids?
False; are sensitive
how is puberty brought upon in males?
decreased sensitivity to neg. feedback by testosterone/estradiol
what kind of feedback loops does the male have after puberty?
negative feedbackloops
some testosterone and mostly estradiol
in prepubertal females, the surge center is sensitive to what kind of feedback of estradiol?
postive
why cant prepubertal females ovulate?
not enough estradiol in the overies
