Summary of the Events of the Menstrual Cycle. Days 1-5 Menstrual Phase Superficial layer of the...
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Transcript of Summary of the Events of the Menstrual Cycle. Days 1-5 Menstrual Phase Superficial layer of the...
Summary of the Events of the Menstrual Cycle
Days 1-5 Menstrual Phase
Superficial layer of the uterus is removed
Bleeding occurs for three to five days Average blood loss is 50-150 mL By day 5 growing ovarian follicles
begin to produce estrogen and the removal of the uterine lining ceases
Days 6-14 Proliferate Phase Rising levels of estrogen produced by the
developing follicles stimulates the regeneration of the functional layer of the uterus
Glands form in the new layer and the blood supply to the layer increases
Ovulation occurs at the end of this phase (Day 12-14) due to the surge of LH in the blood
For the next 7 days the individual will be at their peak chance for conception
Days 15-28 Secretory Phase The corpus luteum of the ovary begins to
produce lots of progesterone This increases the blood supply to the
endometrium Progesterone also causes the endometrial
glands to swell up and they begin to secrete nutrients into the uterine cavity
If a fertilized egg should implant itself, these nutrients would sustain its early developmental stages
Days 15-28 Cont. The fertilized egg would also produce
hormones similar to LH so that the corpus luteum keeps on producing its hormones to sustain it
If the egg is not fertilized, the corpus luteum will degenerate as LH levels fall
Lack of ovarian hormones in the blood also causes the blood vessels that supply the endometrium to spasm (cramps) and twist
This cuts off the supply of blood and leads to cell death
Once this happens, the menstrual period will begin again