Module 3 : Physiology Of Menstrual Cycle Flashcards
Menarche
The very first menstrual flow
Menses
Regular monthly flow in reproductive years
Perimenopausal
Women at the end of her menstrual years
- irregular cycle pattern
- late 40s
- 10 year duration
Menopause
When menstrual cycle ceases for 1 year
GnRF or GnRH
- Gonadotropin releasing factor or hormone
- produced by hypothalamus
- stimulates anterior pituitary to produce its hormones
Hypothalamus
Control center for the menstrual cycle
FSH and LH
- follicle stimulating hormone
- luteinizing hormone
- produced by BETA cells in anterior pituitary
- known as gonadotropins
- stimulate ovaries
FSH
- stimulates growth of follicles
- many follicles will be stimulates but only one follicle will mature with each cycle
LH
- Stimulates follicles but to a lesser extent compared to FSH
- SURGE IN LH RESPONSIBLE FOR OVULATION
- LH supports growth of corpus luteum but does not maintain it ( hCG maintains it in pregnancy)
Estrogen
- secreted from the GRANULOSA cells lining the follicle
- peak secretion occurs just before ovulation
- estrogen must hit threshold so LH can surge
- estrogen cause of proliferation of endometrium
- responsible for secondary sex characteristics
Corpus luteum
- after ovulation the remaining follicle become the corpus luteum
Progesterone
- Secreted by CORPUS LUTEUM
- peak concentration r ached 7 days after ovulation
- induces secretory activity and hypertrophy of endometrium
- inhibits secretion of LH
Relaxin
- Relaxes symphysis pubis during fetal delivery
- helps dilate the cervix to promote sperm mobility
- dilates the cervix in labor during fetal delivery
Stages of the cycle
Menstruation: day 1-5 (first day of a show of blood)
Proliferative phase: day 6-14 (follicular phase)
Ovulation: day 14
Secretory phase: day 14-28 (luteal phase)
Physiology of Menstrual Cycle
- day 1 is bleeding phase
- ovarian hormone levels are low causing hypothalamus produce GnRH
- causes pituitary to produce FSH and LH
- GRAAFIAN FOLLICLE (primary follicle) matures by day 13 and accompany an increase in estrogen
- estrogen hits a threshold which causes LH to surge and induces ovulation at day 14
- Graafian follicle bursts and become corpus luteum
- progesterone increase and estrogen decreases
- corpus luteum regresses if no fertilization occurs and progesterone decreases
- withdrawal of hormones causes menstruation to begin again
Symptoms
- mittelschmerz
- may have fluid retention or weight gain in luteal phase
- rise in body temp at ovulation due to progesterone
Proliferative phase - endometrium
- hypoechoic halo
- echogenic edge of endometrium
- hypoechoic endometrium in the proliferative phase
- apposing endometrial lining
- THREE STRIPE PHASE
Secretory phase - endometrium
- hypoechoic halo (basal layer)
- hyperechoic endometrium
Menstrual phase - endometrium
- endometrium very thin
- may even see blood within the canal
Postmenopausal endometrium
- very thin 1-5mm
- if greater than 5mm may be cancer
- on HRT endometrium thicker
Visualizing endometrium
- try to get perpendicular to endometrium
- retroflexed difficult to see endometrium
Corona radiata
Layer around the egg that giver nutrients
Zona pellucida
Doesn’t allow more fertilization to occur after first fertilization
Granulosa cells
Produce estrogen
Cumulus oophorus
- when the ovum protrudes from the wall of the follicle into the follicular fluid
- sign that ovulation is about to occur
Endometrial phases during menstruation
- proliferative phase: spiral arterioles undergo lengthening via mitosis
- after ovulation and with progesterone influence the endometrium become edematous
- without fertilization the corpus luteum degenerates and estrogen and progesterone decrease
- endo shrinks causing circulation to be cut off
- necrosis sheds
- with fertilization endo thickens further due to increases progesterone from corpus luteum
- high levels of estrogen and progesterone suppress hypothalamus
Corpus albicans
Forms when corpus luteum degenerates
- leaves a white scar
Corpus fibrosum
When a follicle does not rupture
- corpus luteum does not form
- liquid gradually absorbed and the follicle regresses
- a scar is formed
