Week 2 - Female Reproductive Physiology Flashcards
Label External anatomy
Label the Internal Genitalia
What is the function of the uterus?
- Receive, retain and nourish a fertilised ovum
Glands in the mucosa of the ______ secrete mucous that block spread of bacteria into body of uterus and vagina
Cervix
What are the 3 layers that the Uterine wall is composed of?
- Perimetrium -> outermost
- Myometrium -> bulky muscular layer
- Endometrium -> mucosal inner layer
What layers make up the Endometrium?
- A functional layer that undergoes cyclic changes due to ovarian hormones and is shed during menstruation
- a basal layer which is unresponsive to ovarian hormones
What is Prolapse of the Uterus?
Stretching and tearing of ligaments and pelvic floor muscles during
childbirth can result in the unsupported uterus sinking down through the
external opening of the vagina
What are the Fimbriae?
finger-like projections that sweep over the ovary to capture the oocyte
Where does the oocyte travel through in the Fallopian tubes?
through the infundibulum and then the ampulla (place that fertilisation usually occurs
What are the Ovaries? and what do they do
Two small almond-shaped organs that produce female gametes (oocytes/eggs) and secrete female sex hormones (estrogen and progesterone)
What parts do the Ovaries consist of?
Medulla -> inside region that is highly vascularised
Cortex -> outer region where follicles are matures to release oocytes
What is the Ovarian cycle?
refers to the series of changes in the ovary during which
the follicle matures, the ovum is shed, and the corpus luteum develops
What are the steps of Ovulation?
- The mature follicle becomes so large that it bulges from the external ovarian surface
- Ovulation expels the secondary oocyte and surrounding cumulus cells into the peritoneal cavity
- The cumulus-oocyte-complex is swept up by the fimbriae into the fallopian tube
What are the phases of the Ovarian Cycle?
- The Follicular phase (d1-14): follicle growth with ovulation occurring at
the end of this stage - The Luteal phase (d15-28): period of corpus luteum activity
What are the steps in Follicle Growth?
- Primordial follicles are present within the ovary before birth
- Primordial follicles are activated and develop into primary follicles
- Granulosa cells proliferate, a theca layer forms – the follicles are now in the preantral stage
- Granulosa cells secrete follicular fluid, which forms an antrum in early antral follicles
- Approximately 95% of all large antral follicles undergo a degenerative process called atresia
- The antrum of the dominant follicle continues to expand until the cumulus oophorus forms
- As ovulation approaches, the cumulus-oocyte-complex separates from the follicle wall
What is the Corpus Luteum?
- forms in ovary from remnants of ovulating follicle
- made of enlarged granulosa and thecal cells
- degenerates after 10 days if no pregnancy occurs eventually forming corpus albicans
Hormonal Control of Ovarian Function visualised
Steps in Hormonal Control of Ovarian Function
- Hypothalamic GnRH stimulates production and release of LH and FSH by the anterior pituitary
- FSH acts on granulosa cells, while LH acts on thecal cells (due to receptor expression)
- LH stimulates thecal cells to produce androgens, which are converted to estrogen in granulosa cells
- The rising estrogen levels exert negative feedback on the hypothalamus and pituitary
- Inhibin, produced by granulosa cells, acts back on the pituitary to further reduce FSH levels
- Only the dominant follicle survives this dip in FSH – the remaining growing follicles degenerate
- The dominant follicle now responds to both FSH and LH – estrogen production rises
- High circulating estrogen briefly exerts positive feedback on the hypothalamus and pituitary
- The net result of high estrogen is the LH surge (due to increased production and release of LH)
- The LH surge stimulates many events that lead to ovulation
- LH surge also stimulates the reactions that convert granulosa/theca cells into the corpus luteum
- The corpus luteum produces progesteone, estrogen and inhibin, which exert negative feedback
- The cycle starts anew
Describe Day 1-5 of the Menstrual Cycle - Menstrual Phase
- shedding of functional layer of endometrium
- estrogen and progesterone are low
- prostaglandin levels increase and cause vasoconstriction of spiral arterioles and uterine contractions
- ischemic endometrial cells die
- after initial period of vascualr constriction, spiral arterioles dilate -> haemorrhage through the weakened capillary walls
- the Stratum Functionalis sloughs off
Describe Day 6-14 of the Menstrual Cycle - Proliferative Phase
- rebuilding of the functional layer of endometrium
- rising estrogen levels cause:
- promotes progesterone receptor expression on endometrial cells
- thins the cervical mucus allowing passage of sperm into the uterus at the time of ovulation
- ovulation occurs at the end of the proliferative phase
Describe Day 15-28 of the Menstrual Cycle - Secretory Phase
- Progesterone levels rise rapidly and prepare the endometrium for implantation
- glands and stroma enlarge, arteries elongate, etc
- Progesterone causes cervical mucus to thicken forming a barrier to sperm and bacteria
- progesterone inhibits prostaglandin-induced contractions of myometrium
- if fertilisation does not occur, corpus luteum degens
Summary of Menstrual Cycle
