Menstruation Flashcards
What is the purpose of menstrual cycle
- Transport gametes to site of fertilisation
2. Provide suitable site for fertilisation
What stages are there of the menstrual cycle
- Menses
- Follicular
- Luteal
What hormone dominated pre ovulatory part of cycle?
Oestrogen
What surges just before ovulation? And when?
LH 36 hours before
What happens as FSH levels rise in the first 10 days?
Oestrogen is produced and inhibits LH
What happens in menstrual phase?
First 5 days.
- Degeneration of endometrium
- Progesterone inhibits LH and corpus Luteum degenerates
- Lutein cells become less responsive to LH one week after stimulation
What happens when oestrogen promotes a positive feedback loop?
LH and FSH no longer inhibited. LH stimulates ovulation.
Oocyte released into uterine tube
What is released when there is slow GnRH pulse frequencies ?
FSH stimulated
What is released when there is high GnRH pulse frequencies
LH
What dies oestrogen do when it’s levels rise
Negative feedback on FSH and positive feedback on LH
When do follicles rupture
14-36 hours post LH surge
When is secretory phase
Day 15-28
What does LH do?
Promotes endometrium thickening. Maintains CL for a week
What is Zona Pelucida made of?
Glycoproteins
What is oocyte of primordial follicle suspended in?
Meiosis 1 prophase
Theca interna secretes what?
Androgen (precursor of oestrogen) in response to LH
Granulose cells secrete what? What does this inhibit?
Oestrogen inhibits FSH and LH
FSH and oestrogen together promote what after?
LH receptors in Antral stage by positive feedback
What stage of oogenesis is stimulated by LH?
Pre ovulatory stage
What is first polar body?
After meiosis 1 is complete, one daughter cell has less cytoplasm and doesn’t go on to become secondary oocyte. Both undergo meiosis 2.
In ovulation stage of oogenisis, what is a grown matured follicle called?
Graafian follicle.
In ovulation phase of oogenesis, LH promotes what?
Collageneses, to weaken follicular wall to release ovum. Theca external release lysosomes to dissolve follicular capsule . Angiogenesis (blood vessels breaking) so increase follicular swelling to cause rupture
What is mean loss of blood during menstruation ? How much risks anemia.
43ml. More than 60ml risks anemia
What is first polar body a product of
Meiosis 1
How does fertilisation happen?
Acrosomal head of sperm binds to sperm receptors on Zona pellucida. Acrosin penetrates through zona pellucida. Sperm fuses to Vitelline membrane of oocyte. Sperm is then absorbed through into cytoplasm and zona pellucida hardens so multiple sperm doesn’t fertilise oocyte. Meiosis 2 continues to make zygote.
What does progesterone do to endometrium
Glandular secretion and spiral arteries to develop . Increase blood supply to promote differentiation of cells, receptivity to embryo and cervical music thickening.
In Cleavage, what day does morula form?
3 days.
What does trophoblasts secrete
hCG to keep corpus luteum alive. So progesterone and oestrogen continue to rise
What are histiotrophs?
Under influence of progesterone, endometrial glands produce secretions (histiotrophs)z they contain glucose Oli homered and glycoprotiens. They provide nutrient support to early embryo. Glands regress after 11 weeks
When can the early embryonic scan be done?
Transvaginally- at the time of missed period
Trans abdominal- 5 weeks from LMP
Can do early USS if gestation sac- day 12-13 of development (27 days from LMP)
What is fetal pole?
Gestation sac
When is pregnancy viable
When heart beat can be seen.
TV- 5.5 weeks post LMP
TA- 6 weeks post LMP
After LH surge when does follicle rupture?
14-36 hours post LH surge
