menstrual cycle and pregnancy Flashcards
what chemical marker will show a male is infertile
FSH/ testosterone
what hormone causes production of sperm
FSH
what is follicular development dependant on
gonadatropin
two stages of menstrual cycle
follicular
luteal
what happens in the hpg axis
. The hypothalamus secretes GnRH.
- GnRH travels down to the anterior pituitary gland and binds to receptors on the gland.
- This promotes the release of LH (luteinizing hormone) and FSH (follicle-stimulating hormone).
- LH and FSH travel in the bloodstream to the ovaries.
- When LH and FSH bind to the ovaries they stimulate the production of oestrogen and inhibin
- Increasing levels of oestrogen, progesterone and inhibin have a negative feedback effect on the pituitary and hypothalamus.
- This leads to the decreased production of GnRH, LH and FSH.
- This, in turn, results in decreased production of oestrogen and inhibin.
- If a woman becomes pregnant, GnRH, FSH and LH remain inhibited, causing menstruation to cease.
what happens in the follicular phase of menstrual cycle
increase in levels of gnrh causes FSH to increase
leads to follicular maturation- which releases oestrogen
a single follicle will reach full maturation
continues to secrete oestrogen
high levels of oestrogen will stimulate LH
this causes follicle to become thin and rupture to make a secondary oocyte
Secondary oocyte formed which will be released into fallopian tube w fimbria
name of follicle that reaches full maturity in follicular phase
graafian follicle
increase in oestrogen in the follicular phase causes
endometrial thickening
thinning of the cervical mucus to allow easy passage of sperm
inhibition of lh production by ant pituitary
what happens in the luteal phase
graffian follicle into corpus luteum
releases ; progesterone, inhibin and oestrogen
endometrium becomes receptive to implantation
levels of LH and FSH decrease - corpus luteum degenerates
decrease in level of progesterone stops triggers menstruation and the cycle repeats
what happens during days 0-4 of fertilisation
day 1- sperm acrosomal reaction @ zona pellucida
M and F pronuclei form , 2n cells
day 2+3 - cleaving
day 4- morula forms 8–16 cells same size but more compacted
pathway of sperm
uterine tube
ampulla
corona radiata
zona pellucida
effects of progesterone in the luteal phase
endometrium becomes receptive to implantation of a blastocyst
-ve feedback causing decreased LH and FSH
an increase in woman’s basal body temp
what is an acrosome
layer on head of sperm
how does sperm breakdown the zona pellucida
releases acrosin
acrosomal reaction two parts
acrosin release
sperm and egg fuse
what happens during days 5-7 of fertilisation
day 5- 16-32 blastocyst , inner cell mass and outer cell masses form
day 6- hatching , ZP breakdown
Day 7- blastocyst implants in endometrial lining
what follicle is formed in the fetal ovary
primordial follicle
stages of follicular development
primordial primary secondary luteinising corpus luteum regression of follicle
what is follicular development dependant on
GONADATROPIN
What hormones are involved in pregnancy
oestrogen progesterone hcg prolactin relaxin oxytocin prostaglandins
cardio and resp related changes a woman faces during pregnancy
cardio- increase in plasma volume, cardiac output and blood pressure
resp= increase in tidal volume and resp rate
3 stages of labour
1- active phase
2- pushing phase
3- placenta delivery
what happens in the active phase of labour
irregular then true contractions
cervix dilates
what happens the pushing stage of labour
delivery of the baby
what happens in the placental delivery
placenta detached from endometrial wall
how is the baby pushed out
- -head of baby pushes against cervix
- sends impulses to brain
- pituitary gland releases oxytocin
- oxytocin stimulates uterine contractions and pushes baby towards the cervix
what hormones help to widen the cervix
relaxin and oestrogen
what hormone stimulates uterine contractions
oxytocin
three layers of the uterus
endometrium
myometrium
perimetrium
vagina epithelia
stratified squamous non keratinising
what is cervical ripening
Cervical ripening is a normal process of softening and opening the cervix before labor starts
main function of the placenta
passageway of nutrition between mother and child
fetal respiration
barrier between maternal and fetal circulation
structure of placenta
discoid shaped
two surfaces fetal and maternal
purpose of fetal surface of placenta
covered in amnion
amniotic membrane secretes amniotic fluid
under the amnion is the chorion
Role of fsh in the hpg axis
Stimulates development of the ovarian follicle , most sensitive one becomes the dominant Graafian follicle
Role of lh in the hpg axis
Causes the Graafian follicle to change into corpus luteum which begins to produce progesterone
What does the corpus luteum produce
Progesterone
what happens if fertilisation occurs
if an ovum is fertilised it produces HCG
hcg prevents degeneration of the corpus luteum
continued production of progesterone prevents menstruation
placenta takes over
how is the placenta formed with chorion frondosum
The cells in the chorion frondosum proliferate and become the placenta
hormones that the placenta secretes
hCG – supports corpus luteum
hcS (somatotropin) – stimulates mammary development
progesterone and oestrogen – supports maternal endometrium
relaxin
process of fertilisation
Around ovulation the primary oocyte undergoes meiosis leaving a haploid cell- the other 23 chromosomes become a polar body.
Sperm attempt to penetrate the corona radiata and zona pellucida to fertilise the egg, usually only one sperm will get through before the layers shut the other sperm out
When a sperm enters, the 23 chromosomes of the egg multiply into 2 sets. One set combines with the 23 chromosomes from the sperm and the other 23 create the second polar body
Where does fertilisation occur
Fertilisation occurs at ampulla of fallopian tube
