Puberty in Female Lecture Notes Flashcards
What is puberty?
The acquisition of reproductive competence; a developmental period characterized by a broad range of physiologic changes necessary for the acquisition of adult sexual and reproductive maturity; characterized by maturation of the genital organs and development of secondary sex characteristics.
What is puberty specifically in a female?
Involves a transition from a state of ovarian inactivity to one in which regular ovulations occur. Criteria are age at first estrus (heat), age at first ovulation, and age at which female can support pregnancy without deleterious effects
What is the mechanism of onset of puberty?
It’s unknown
What is the HPG axis?
The hypothalamic-pituitary-gonadal axis, which, when matured into a fully active state, is an neuroendocrine cascade ensuring gonadal activation, sex steroid secretion, and gametogenesis
The hypothalamus is inherently _____. Why?
Female. Our entire body system is first developed as a female until the fetus is like six weeks old.
What is the GnRH surge center and tonic center?
The surge center is responsible for GnRH surge release, and the tonic center is responsible for tonic GnRH release. Until puberty, the surge center lies dormant, and stimulation of the preovulatory GnRH surge is necessary for the first ovulation to initiate the onset of puberty
What are the two populations of hypothalamic kisspeptin neurons?
1) The preoptic area kisspeptin neurons project to the cell body and proximal dendrites of GnRH neurons, where they integrate gonadal steroids and (when required) circadian inputs to help drive the preovulatory surge of LH
2) The arcuate kisspeptin neurons project to the distal dendron o the GnRH neuron and are involved in generating pulsatile secretion of LH
Where are GnRH-secreting neurons?
scattered from the rostral pre-optic area (POA) to the caudal hypothalamus
What is GnRH?
A master regulator of the HPG axis. It’s a decapeptide that is synthesized in hypothalamic neurons and is secreted into the hypophyseal portal circulation to act primarily on the anterior pituitary
What is the half-life of GnRH?
2-4 minutes
What is the difference in GnRH secretion before and after puberty?
Before puberty, GnRH neurons in the tonic and surge centers release low amplitude and low frequency pulses of GnRH. After puberty, the tonic center controls basal levels of GnRH, the pulse frequency increases. The surge center controls the preovulatory surge of GnRH.
How does GnRH regulate gonadotropin secretion?
It binds to the gonadotropin-releasing hormone receptor (GnRHR) on the cell surface of an anterior pituitary cell, which induces synthesis of gonadotropins (FSH and LH)
What is required for long-term stimulation of gonadotropin synthesis and secretion?
Pulsatile GnRH secretion
Contrast FSH and LH in terms of GnRH pulse frequencies
FSH is preferentially stimulated at low GnRH pulse frequencies, and LH is preferentially stimulated and high GnRH pulse frequencies
What do FSH and LH do?
Regulate critical aspects of mammalian sexual maturation and reproductive function, including gametogenesis, steroidogenesis, and ovulation
