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The menstrual cycle
Transcript of The menstrual cycle
establishing the ovarian cycle
Ovarian Cycle & Uterine cycle are linked
The menstrual cycle
Breast development and maintenance
Adding fat to breasts, hips, thighs during puberty
Improving bone strength and density
Accelerating bone maturation and bringing epiphyses to closure, completing growth
Growth of the uterus
Development of the endometrial lining to a thickness necessary to support pregnancy and menstruation
Thinning of cervical mucus at ovulation
Promoting and maintaining vaginal mucosal thickness and secretions
Serving as the primary feedback to the brain of sex hormone levels
Participating in triggering ovulation
Preservation of egg cells
Effect on lipids
Estradiol - A very busy hormone, responsible for many things:
Uterine cycle, closer look:
Ovarian cycle, a closer look
Adult cyclic pattern achieved & hormonal interactions stabilize – events heralded by menarche (1st menstrual period).
from Doshi & Agarwal, 2013
Problems with the Menstrual Cycle:
PMS: Pre-menstrual Syndrome
a group of symptoms that start 7 to 14 days before menses
Physical fluctuations during cycle are normal.
WHY? Estradiol & Progesterone levels fluctuate dramatically (especially during the premenstrual phase)
PMS a misogynistic myth?
Is PMS a way of making women’s normal cycle dysfunctional? (labeled a psychological disorder in the DSM)
Are we just linking ailments to our reproductive organs in a way that makes women less equal to men?
– failure to menstruate by age 18
Prevalence = 1% of women in US
thyroid disorders, problems with adrenal cortex or pituitary gland
Genentics - Mayer-Rokitansky-Kuster-Hauser syndrome mullerian agenesis or dysgenesis; AIS; Turner’s syndrome - ovaries undergo atresia (absent/closed), no primordial oocytes
– uterine bleeding blocked due to imperforate hymen
– cessation of periods any time between menarche and menopause, associated with stress
Low body fat, low dietary fiber (impact estrogen)
Endorphins can inhibit GnRH
Abnormal uterine bleeding
Make sure that bleeding is coming from the vagina and is not from the rectum or in the urine. Inserting a tampon into the vagina will confirm the vagina, cervix, or uterus as the source of bleeding.
Careful history is important
See your gynecologist for a complete exam
– painful menses (without any evidence of physical abnormality)
Cramps – directly related to prostaglandins
(NSAIDS or PG inhibitors)
Ibuprofen, naproxin or asprin
Home remedies: Hot water bottle, heating pad, exercise, yoga, orgasm
Non-Western remedies: Accupuncture
Oral contraceptives (which reduce prostaglandin production)
- Physical abnormalities can result in painful periods:
Pelvic inflammatory disease & cervical stenosis
Fibroid tumors (increased flow, clotting, pain)
MYTHS about the Menstrual Cycle
No swimming, intercourse, making decisions during your period...
Some cultures very oppressive towards menstruating women.
LUNAR CYCLE: 29.5 days
Why did mestruation evolve?
GnRH - Gonadotropin releasing hormone
FSH - follicle stimulating hormone
LH - Leutenizing hormone
LH principally stimulates androstenedione production, and to a lesser degree testosterone production in theca cells. Androstenedione is then transported to the granulosa cells where it is aromatized to estrone (when FSH high) and finally converted to estradiol by 17-β-hydroxysteroid dehydrogenase type I.
endocrine events: adrenarche, gonadarche, and activation of the growth axis
In mammals, Oogonia divide to form a limited # of precursor cells.
In humans, this process takes from 14 to 55 years.
"An extended period of swelling (not associated with ovulation) coupled with ambiguity in peak receptivity may have significance in the evolution of promiscuous sexual behavior"
The female will only allow the male to mate during a restricted time coinciding with ovulation
what about concealed ovulation in humans?