Lect 28: uterine cycle Flashcards
endometrial (uterine) cycle consists of what 3 phases
- menstrual phase: 0-4 d
- proliferative phase: 5-14 d
- secretory (progestational) phase: days 15-28
describe uterine cycle: menstual phase
- when does it occur
- where does it link with ovarian cycle
- discharge of blood and endometrial debris from vagina
- first day of menstruation marks new cycle
- menses occurs 14 days after ovulation
- coincides with end of ovarian luteal phase
function of release of prostaglandins during menstrual phase
- causes vasoconstriction of endometrial vessels which disrupts blood supply and results in death of endometrium
- stimulates mild contractions of uterium myometrium which helps expel blood and debris into vagina
Proliferative phase in dominated by what hormone
- estrogen
describe proliferative phase
- where does it link with ovarian cycle
- what is occuring
- begins with last portion of ovarian follicular phase: lasts from end of menstruation to ovulation
- endometrium starts to repair itself and proliferate under influence of estrogen from newly growing follicles
- peak estrogen levels trigger LH surge -> ovulation
When does uterus enter secretory/progestational phase
after ovulation when new corpus luteum is formed
what is occuring during secretory/progestational phase
- progesterone secreted from corpus luteum converts endometrium to highly vascularized, glycogen-filled tissue
- endometrial glands actively secrete glycogen
what happens during secretory/progestational phase if fertilization and implantation do not occur
- corpus luteum degenerates
- new follicular phase and menstrual phase begin once again
effects of estrogen on fallopian tubes
increases number of cilia and thier rate of beating, drawing the ovum into the tube
effects of estrogen on myometrium
increases oxytocin receptors and contractions
effects of estrogen on endometrium
- thickens, increases permeability and blood supply
- synthesizes receptors for progesterone on uterine cells
effects of estrogen on cervix and vagina
- cervix: makes environment more alklaline and watery and increases distensibility, making birthing easier
- vagina: increases vaginal secretions
effects of estrogen on mammary glands
- required for growth
effects of estrogen on skeletal system/Ca2+ metabolism
- facilitates calcium uptake into bone
- antagonizes PTH
effects of estrogen on skin
- inhibits body and facial hair growth
- promotes pubic and axillary hair growth
effects of estrogen on kidney electrolytes
- increases absorption of Na, Cl-, and H2O, contributes to bloating
Effects of Progesterone on Uterus
- needs estrogen prior to stimulation
- increases development, differentiation of endometrial glands, converts uterus into actively secreting tissue
- induces placenta formation
- decreases contractility
Effects of Progesterone on cervix and vagina
- antagonizes estrogen!
- cervix
- decreases distensibility
- thick, acidic, mucus, poor environment for sperm
- vagina
- decreases proliferation of epithelial layer
Effects of Progesterone on mammary gland
increases branching of ductal system
Effects of Progesterone on body temp
increases temp following ovulation and increases appetite
Effects of Progesterone on kidney electrolytes
decreases Na+ reabsorption
which hormone is responsible for growth and development of vagina, uterus, and oviducts: organs essential to ovum transport and zygote implantations
estrogen
which hormone is the hormone of pregnancy responsible for implantation of zygote and maintenance of pregnancy state
progesterone
- acts on estrogen primed tissues and typically antagonizes estrogen’s effects
PMDD
premenstrual dysmorphic disorder
when does menopause typically occur ? what triggers onset
45-55, hypothalamic changes may trigger onset
period of transition through menopause is called
climacteric
what is menopause
- decline in fertility associated with a decline in ovarian function
- related to a drop in critical mass of primordial follicles
Primary cause of perimenopause is a decrease in follicular pool. What are the next steps
- inhibin decreases -> FSH increases -> acceleration of follicular maturation -> shorter cycle
What happens in perimenopause when the follicular pool decreases even further?
- E2 (estradiol (E2) decreses -> delayed + feedback -> longer cycle
- insufficient E2 -> no + feedback -> anovulatory
What happens in menopause when the follicular pool decreases even further?
- E2 very low -> LH and FSH high
- cycle arrest
when is menopause diagnosed
- FSH > 30 mIU/ml
- no menses for 12 months in women of typical age range
What is ERT and when is it used
- estrogen only
- used if woman has had hysterectomy
What is HRT and when is it used
- estrogen + progesterone
- typical treatment
- progesterone opposes estrogen effects on uterus
MOA of progesterone only oral contraceptive pills
- prevent ovulation by negative feedback on the anterior pituitary, preventing LH surge
- thickening of cervical mucus which reduces sperm motility
- decreased uterine glycogen production, which impairs blastocyts survival and interferes with implantation
MOA of Plan B
- high dose combination of estrogen + progesterone
- suppress ovulation
- premature degeneration of corput luteum
