Condensed Menstrual Cycle PDF

HAPS Anatomy & Physiology LOs MODULE R: Reproductive System Oogenesis, folliculogenesis, and the ovarian cycle – Describe a typical ovarian cycle and explain how the process of folliculogenesis spans multiple ovarian cycles. – Define ovulation, and explain the...

HAPS Anatomy & Physiology LOs MODULE R: Reproductive System Oogenesis, folliculogenesis, and the ovarian cycle – Describe a typical ovarian cycle and explain how the process of folliculogenesis spans multiple ovarian cycles. – Define ovulation, and explain the role of luteinizing hormone (LH) in ovulation. – Describe endocrine regulation of oogenesis, folliculogenesis, and the ovarian cycle. Uterine (menstrual) cycle – Name the phases of the uterine (menstrual) cycle, and describe the anatomical changes in the uterine wall that occur during each phase. – Describe the correlation between the uterine and ovarian cycles.  Human Menstrual Cycle Hypothalamic-pituitary-ovarian axis tightly regulates human menstrual cycle – Gonadotropins released from pituitary LH, FSH Induce regular changes in ovaries and uterine endometrium and create ovarian and uterine cycles Menstrual Cycle – Combined ovarian and uterine cycle – Average human cycle 28 days (length of lunar month) – Range ~25-30 days (follicular phase of the ovarian cycle allows for some variety)  Menstrual Cycle Ovarian Cycle + Uterine Cycle = Menstrual Cycle – Menstrual (destructive) Phase Days 1-5 Menstruation Endometrium sloughs off – Follicular (proliferative/estrogenic) Phase Days 5-14 End of menses to ovulation Ovaries secrete estrogen as follicles mature Uterine lining grows thicker and prepares for fertilization – Luteal Phase Days 14-28 From ovulation to menstruation Corpus luteum secretes estrogen and progesterone Uterine lining enter the secretory phase and becomes ideal place for and egg to implant  Ovarian Cycle Follicular Phase – Maturation of ovarian follicles to prepare one of them for release during ovulation. Follicles begin to secret estrogen. Late Follicular Phase – Dominant follicle becomes the Graafiin follicle and is ready for ovulation. Estrogen levels peak. Luteal Phase – After ovulation, corpus luteum forms and secretes estrogen and progesterone.  Uterine Cycle Menstrual Phase (Menses) – Progesterone and estrogen levels drop and cause the endometrium to slough off Proliferative Phase – Endometrial lining rebuilds and grows thicker under the influence of estrogen Secretory Phase – Under the influence of progesterone, the endometrium becomes ideal place for fetus to grow  Role of Hormones in Menstrual Cycle Hypothalamic Hormone – Gonadotropin Releasing Hormone Stimulates the secretion of FSH and LH Gonadotropin Hormones – Follicle Stimulating Hormone (FSH) Stimulates immature follicles to grow and produce a mature egg – Luteinizing Hormone (LH) Allows for the release of the egg from the ovary (ovulation) Sex Hormones – Estrogen and Progesterone Provide negative feedback so more eggs are not produced and remain high during pregnancy If fertilization does not occur, their levels fall and cause menstrual bleeding  Menstrual Phase (Days 1-5) Uterus – Functional zone degenerates and sloughs off Spiral (coiled) arteries spasm – Blood flow is interrupted (ischemia) – Endometrial functional zone dies – Uterus contracts (cramps) to expel endometrial tissue – Total blood (tissue) loss is about 1-8 oz Ovary – Leftover corpus albicans regresses (after 1 day) – Ovaries contain small tertiary follicles and atretic follicles Hormones – All hormones low at start of menses  Follicular/Proliferative Phase (Days 5-14) Uterus – Endometrium grows (proliferates) (in response to estrogen) – Uterine glands enlarge – Vascularization (new spiral arteries) Ovary – Rapid growth of follicles (in response to FSH) – Few large follicles remain at days 10-12 – One Graafian follicle (if two- TWINS!) by day 13 Hormones – Estrogen increases and peaks at day 13 (large ovarian follicles with granulosa cells) – LH surge triggered 1-2 days after Meiosis I finally completes in Graaffian follicle Ovulation occurs  Ovulation Feedback Moderate estrogen levels block GnRH release – Normal negative feedback During ovulation, VERY high estrogen levels enhance GnRH release – Positive feedback – GnRH triggers LH surge which triggers ovulation  Luteal/ Secretory Phase Uterus – Endometrium becomes thick and spongy – Glands secrete nutrients for embryo Ovary – Corpus luteum forms – Breasts enlarge and become sensitive – If egg is not fertilized, corpus luteum degrades into corpus albicans 4 days before menstruation Hormones – Corpus luteum secretes estradiol and progesterone (theca cells) – Negative feedback blocks FSH and LH – As corpus luteum degrades to corpus albicans (4 days before menstruation), hormone levels drop – GnRH inhibition lifted → new cycle starts  Variations in Menstrual Cycles Difficult to exactly predict ovulation in advance – Usually 14 days before menstrual phase Physical cues – Mittelschmerz (pain from follicle rupture) – Body temp increases 0.5-1 degree during luteal phase – Spinnbarkeit (cervical mucus) Pre-ovulatory (5-7 days) thick Post-ovualtory (1-3 days) thin Lab tests: LH levels  Contraceptives Contain estrogen and progesterone (combination pill) or progesterone only (mini pill) Stops ovulation by slowly releasing progestin into the body. Progestin negative feedback works at the hypothalamus to decrease GnRH which in turn decreases FSH and LH Estrogen inhibits follicular development because its negative feedback causes slowed FSH secretion- not as prominent as the progesterone’s effect Helps thicken cervical mucus Thins the endometrium making it difficult for a fertilized egg to implant  Premenstrual Syndrome 3-10 days BEFORE Menstruation 70-90% experience some of the following – Physical symptoms Cramps, backache, nausea, dizziness, fatigue, breast tenderness, swelling of hands/feet, fluid retention/weight gain, acne, migraine – Psychological Tension, irritability, depression, anxiety, food cravings, lack of focus Cause? Withdrawal of estrogen and progesterone? Treatment – Progesterone replacement (doesn’t work on severe cases) – GnRH blockers (menopausal side effects) – Antidepressant during luteal phase – Healthy lifestyle  Menstrual Variations Dysmenorrhea – Pain DURING menstruation Menstrual cramps- Uterine and back pain – Ischemia plus uterine contractions – Prostaglandins (PG) in menstrual fluid may increase contractions – Treatment » NSAIDs (prostaglandin inhibitor) Prostagland » Exercise ins Amenorrhea – Missing menstrual cycle Muscle – Primary: No menstrual cycle by age 15 contractions, May be something wrong with development Inflammation, – Secondary: 3-6 months without cycle pain Pregnancy, menopause (late 40s), diet, exercise Oligomenorrhea – Skipped cycles; PCOS, – diet, exercise – More common in thin build women (some athletes) – Prevalence 2-5% in general; 1-44% in athletes