reproduction physiology and biochemistry Flashcards
what are the 2 gonadotrophic hormones that the pituitary gland secretes?
FSH
LH
what is the purpose of FSH?
Male: causes the testes to produce sperm (spermatogenesis)
Female: causes the growth of ovarian follicles (oogenesis) and it causes the ovary to secrete oestrogen
what is the purpose of LH?
Male: causes the testes to secrete testosterone
Female: causes ovulation and it causes progesterone production by the Corpus Luteum
what type of hormone is GnRH
neuropeptide hormone
which hormone is stimulated in high frequency GnRH pulses?
LH
which hormone is stimulated in low frequency GnRH pulses?
FSH
an increase in which hormone reduces frequency of GnRH pulses?
progesterone
Do GnRH neurons have receptors for oestrogen and progesterone?
No, so therefore indirect regulation
what are the phases of the menstrual cycle?
follicular phase
then ovulation
then luteal phase
what actually regulated GnRH pulsitility?
kisspeptide receptors
what stimulates ovarian follicle growth (and therefore a rise in oestrogen levels) ?
FSH
what does the rise in oestrogen levels lead to?
temporarily lower FSH
THEN once a threshold is reached there is an increase in FSH and a surge in LH
what does the LH surge lead to?
progesterone increase
what is folliculogenesis?
with rising oestrogen levels (associated with follicle growth), FSH levels initially decrease (negative feedback at HPA-axis) so only the follicle able to cope with this fall in FSH (likely to be the one with the most FSH receptors and highest vascularity) can survive this decrease. Others are lost
when does the corpus luteum form?
under the influence of LH
how does the corpus luteum form?
granulosa and theca cells transform to luteal cells
what hormone is increased in the formation of the corpus luteum?
progesterone
how does the increase in progesterone in the formation of the corpus luteum occur?
LH stimulates angiogenesis (ensures efficient delivery of cholesterol (substrate for progesterone synthesis))
LH stimulates enzymes involved in conversion of cholesterol to progesterone
what is the main functions of oestrogen?
Increase the thickness of the vaginal wall
Regulate the LH surge
Reduce vaginal pH through increase in lactic acid production
Decrease viscosity of cervical mucus to facilitate sperm penetration
what is the function of progesterone?
Maintains the thickness of the endometrium
Responsible for infertile thick mucus (prevent sperm transport and help prevent infection)
Relaxes the myometrium (smooth muscle). Functional progesterone withdrawal thought to regulate parturition (birth)
what the optimal route for sperm to pass through?
through PG (primary grooves) and SG (secondary grooves), avoiding thick mucus and immune cells
which cells take up most of the testosterone?
Sertoli cells (about 90%)
what is the role of testosterone during spermatogenesis?
Maintains the integrity of the blood-testes barrier
Release of mature spermatozoa from Sertoli cells by influencing peritubular myoid cells
