Menstrual cycle Flashcards
What are the three phases of the uterine cycle?
Menses (shedding of endometrium - ‘period’)
Proliferative (rapid growth of endometrium)
Secretory (preparation for implantation)
What are the actions of gonadtropic hormones in the menstrual cycle?
FSH stimulates growth of follicle (increased granulosa cells which secrete oestrogen)
LH stimulates production of thecal cells that surround the follicle and produce androstenedione which is converted to oestrogen by granulosa cells
What are the phases of the ovarian cycle?
Pre-ovulatory phase (growth of follicle and preparation for ovulation)
Ovulation (approx. day 14 although variable - caused by surge in LH but no surge in FSH due to actions of Inhibin)
Post-ovulatory phase (follicle develops into corpus luteum which secretes high levels of progesterone in preparation for implantation)
What is the fate of the corpus luteum both in the case of fertilisation and in the case of no fertilisation?
Fertilisation = corpus luteum persists due to levels of LH and continues to secrete progesterone and maintain endometrial lining
No fertilisation = lack of FSH and LH causes atrophy of the corpus luteum resulting in a drop in oestrogen and progesterone levels triggering the end of the luteal phase (and cycle starts again as endometrial lining is shed)
What are the 3 layers of the uterus (from lumen outwards)?
Stratum Functionalis (this is the layer shed during menses) Stratum Basalis (has blunted hormone responses) Myometrium (produces specialised contractile waves throughout cycle and forms 'placental bed' during pregnancy)
[Nb. together the stratum functionalis and stratum basalis make up the endometrium]
By what process do steroid hormones act on endometrial cells?
Freely cross cell membrane and activate gene expression through binding with oestrogen and progesterone receptors in the cell nucleus.
Target genes incl. chemokines, cytokines and growth factors which feedback to other cells and recruit immune cells to remodel in response to hormone levels
What is menarche?
A female’s first menstrual period
Average age is 12
What functional windows occur throughout the menstrual cycle?
Regeneration window (approx. days 0-5 during menses phase) Fertile window (approx. 4/5 days pre-ovulation and 1 day post-ovulation) Implantation window (approx. days 19-23 during secretory phase) Selection window (approx. days 23-27 during secretory phase)
What can be used to determine a females fertility window?
Basal body temperature
Spinnability
[Nb. can be used as a rhythm method of natural contraception]
How long does it take for an ovum to be transported from the ovary to the uterus?
Takes 5 days for ovum to travel from release of ovary, down uterine tube and into the uterus after fertilisation
What are the signs and symptoms of abnormal uterine function?
Pain (incl. dyspareunia, mittlesmerch)
Bleeding (incl. menorrhagia, amenorrhoea)
Problems with pregnancy (incl. infertility, miscarriage, ectopic pregnancy)
What is dyspareunia?
Pain during intercourse
What is mittlesmerch?
Pain during ovulation
What is dysmenorrhoea?
Pain during menstruation
What is menhorrhagia?
Heavy menstrual bleeding
