repro 2.1- control of reproductive processes. Flashcards
What does sucessful fertilisation depend on?
- correct number of gametes produced at the right time
- effective transport of sperm from male to female
- successful fertilisation
- support of conceptus, embryo and feotus
- support of neonate
where does the anterior pituatory gland originate from?
an outpouching of the epithleial tissue from the roof of the mouth,
Known as Rathke’s pouch
This then migrates to the adult location
What are the main secretions of the anterior pituatary gland?
trophic hormones.
Where does the posterior pituitary gland originate from?
a growth from the brain, it is therefore made of nervous tissue.
What tissue is the anterior pituitary formed from?
endocrine
what 2 types of hormones are produced in the anterior pituitary gland?
glycoprotein hormones
polypeptide hormones
What glycopeptide hormones are produced in the anterior pituitary?
FSH, LH
TSH
What polypeptide hormones are produced in the anterior pituitary?
growth hormone
prolactin
ACTH
What cell types are found in the anterior pituitary?
gonadotrophs thyrotrophs somatostrophs corticotrophs lactotrophs
How is the anterior pituitary secretions controlled?
by control of the hypothalamus.
releasing hormones travel in the hypophysealcirculation as neurosecretions, and act on the anterior pituitary.
What releasing hormone controls the reproductive hormones?
FSH and LH crelease is controlled by gonadotrophin releasing homrone (GRH)
what’s characteristic about the GRH release?
it’s pulsatile
how can you increase the amounts of LH and FSH released?
increase the frequency or magnitude of pulses.
What are the broad functions of LH and FSH?
act on the gonads to stimulate gamete production, and secretion of gonadal steroids.
What’s the effect of moderate oestrogen levels in a female?
reduction in GnRH levels, normal negative feedback.
What’s the effect of high levels of oestrogen alone?
positive feedback, increases the amount of GnRH released, and therefore is teh basis behind the LH surge.
what’s the effects of progesterone on GnRH release?
Only takes effect in the presence of oestrogen:
- moderate oestrogen- increases the inhibitory effect
- high levels of oestrogen, prevents positive feedback, therefore LH surge.
with regards to the pulsatile nature of GnRH release, what’s the effects of:
a) oestrogen
b) progesterone?
a) oestrogen increases the amount of GnRH per pulse.
b) progesterone affects the frequency of the pulses.
What does inhibin do?
Inhibits the release of FSH
Where is inhibin released from?
granulosa cells of developping follicles in a woman.
sertoli cells in a man.
in the male, what are teh effects of;
LH
FSH
LH binds to Leydig cells, and promotes testosterone secretion
FSH binds to sertolli cells which stimulates inhibin secretion.
in the female, what are the effects of
LH
FSH
LH binds to the theca interna cells, leading to production of androgens, which are converted to oestrogen by the granulosa cells.
FSH binds to the granulosa cells, which produce oestrogen and inhibin.
in the follicluar phase, what are the actions of oestrogen?
- thin, alkaline cervical fluid
- thickening of the endometrium
- thickening and motility of the myometrium
- increased motility of fimbriae
In the luteal phase, what are the actions of progesterone?
- further thickening of the endometrium and myometrium
- thick, acidic cervical fluid
- increased body temperature
If fertilisation occurs, what happens to the corpus leuteum?
It is maintained by human chorionic gonadotropin, which is released from the syncitiotrophoblast of the embryo.
