Menstrual cycle.pptx bams first year physiology

For Basic understanding

1. Menstrual cycle By Dr beena Tripathi S.A.M.C. Jaunpur

2. Menstrual cycle The menstrual cycle is the natural, cyclic process that prepares a woman’s body for pregnancy every month. It is controlled by hormones and usually lasts about 28 days (though it can range from 21–35 days in adults).

3. Menstrual cycle Hypo-pituitary- ovavian axis Ovarian cycle Endometrial cycle

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6. Hypothalmus pituitary ovairan axis Ovaian cycle Endometrial cycle

7. Menstrual cycle Hypothalmus Pituitary Ovary Uterus(endometrium)

8. Hypothalamus –pituitary-ovarian axis Hypothalamic–Pituitary–Ovarian axis, which is the central hormonal system that regulates the menstrual cycle, ovulation, and female fertility.

9. CONTI… 1. Hypothalamus Secretes GnRH (Gonadotropin-Releasing Hormone) in a pulsatile manner. Pulse frequency matters: Slow pulses → more FSH release .Fast pulses → more LH release.

10. CONTI… 2. Anterior Pituitary--Responds to GnRH pulses by secreting: FSH (Follicle Stimulating Hormone) → follicle growth & estrogen production (via granulosa cells). LH (Luteinizing Hormone) → theca cells → androgens → converted to estrogen by granulosa. LH surge → ovulation + luteinization (formation of corpus luteum).

11. Conti… 3. Ovaries Follicles in the ovary secrete : Estrogen → causes endometrial growth, and at high levels, gives positive feedback to trigger LH surge. Progesterone (from corpus luteum) → stabilizes the endometrium and prepares for implantation . Ovaries also produce Inhibin A&B , which negatively regulates FSH.

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13. Relation between insulin,Gnrh &kisspeptin insulin ↑ → Kisspeptin ↑ → GnRH ↑ → fertility supported. Insulin deficiency (starvation/Type 1 DM) → Kisspeptin ↓ → hypogonadism/amenorrhea. Insulin excess (PCOS, obesity) → abnormal kisspeptin signaling → LH excess → infertility

14. Feedback mechanism Low–moderate estrogen → Negative feedback → suppresses FSH & LH. Sustained high estrogen (pre-ovulatory) → Positive feedback → LH surge → Ovulation. Progesterone + Estrogen (luteal phase) → Negative feedback → inhibits GnRH, FSH, LH. If no pregnancy → Corpus luteum regresses → Progesterone & estrogen drop → Menstruation → Cycle restarts. If pregnancy –beta HCG—give message to corpus luteum—continue progesterone srcretion –to support the pregnancy

15. Ovarian cycle Follicular phase Ovulation phase Luteal phase

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17. Ovarian cycle Follicular Phase (Day 1–14, variable) Begins with menstruation. FSH stimulates growth of several follicles .One becomes the dominant follicle → Graafian follicle.Granulosa cells produce estrogen → proliferation of endometrium . Estrogen exerts negative feedback at low levels, but sustained high levels cause a positive feedback → LH surge.

18. Ovarian cycle Ovulation (Around Day 14 in a 28-day cycle) Triggered by LH surge (and partly FSH surge). Oocyte completes meiosis I, arrests in metaphase II. Follicle ruptures, releasing the secondary oocyte.

19. Ovarian cycle Luteal Phase (Day 15–28) Ruptured follicle → Corpus luteum secretes progesterone (+ some estrogen ).Progesterone prepares endometrium (secretory phase) for implantation. If no fertilization → corpus luteum degenerates → corpus albicans. Drop in progesterone & estrogen → endometrial shedding (menstruation). Low hormone levels remove negative feedback → new cycle starts with rise in FSH

20. Primodial germ cell--- epiblast cell—yolk wall(line by endoderm)---genital ridge---gonads

21. Conti.. Primordial Follicle --Flat granulosa cells, quiescent-25–30 μ m Primary Follicle--Cuboidal granulosa, zona pellucida appears 50–60 μ m Secondary Follicle-Multiple granulosa layers, theca begins100–200 μ m Early Antral Follicle--Small fluid-filled spaces -200–400 μ m Small Antral Follicle--Single cavity -2–5 mm Dominant (Graafian) Follicle Large, preovulatory, bulges on ovary surface-18–25 mm (on USG)

22. Time Required for Follicular Development Time Required for Follicular Development Follicle Stage Approximate Duration Primordial → Primary follicle ~ 150–300 days (5–10 months) Primary → Secondary follicle ~ 120–150 days (4–5 months) Secondary → Antral follicle ~ 65 days Antral → Preovulatory (Graafian) follicle ~ 14 days

23. USG findings Ultrasound Note: <5 mm: Microscopic; not seen on transvaginal USG 5–10 mm: Seen as small antral follicles 18–25 mm: Size of mature Graafian follicle, ready for ovulation> Ovulation generally occurs at 18–22 mm

24. CONTI… Ovary Granulosa cells: respond to FSH → produce estrogen + inhibin B. Theca cells: respond to LH → produce androgens (substrate for estrogen synthesis). Corpus luteum: after ovulation, secretes progesterone, estrogen , inhibin A.

25. Endometrial phases of the menstrual cycle 1.menstrual phases(1-5 days) 2.follicular phase(1-13 days, overlaps with the menstrual phase) 3.ovulation phase(14day) 4.luteal phase(15-28 days)

26. Hypo ovarian axis

27. Conti.. Menstrual Phase (Day 1–5)The first day of bleeding is counted as Day 1.The endometrium (inner lining of the uterus) sheds because pregnancy has not occurred.Hormones (estrogen and progesterone) are at their lowest. 2. Follicular Phase (Day 1–13, overlaps with menstrual phase)The pituitary gland releases FSH (Follicle Stimulating Hormone).Several ovarian follicles start maturing, but usually only one becomes dominant.The dominant follicle produces estrogen, which helps in the growth and thickening of the uterine lining.

28. conti … 3.Ovulation Phase (Around Day 14)A surge in LH (Luteinizing Hormone) triggers release of a mature egg from the ovary.This is the fertile window (highest chance of pregnancy). 4. Luteal Phase (Day 15–28)After ovulation, the ruptured follicle becomes the corpus luteum, which secretes progesterone Progesterone prepares the endometrium for possible implantation of a fertilized egg . If pregnancy does not occur, the corpus luteum degenerates, progesterone falls, and the cycle restarts with menstruation.

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33. Function of estrogen 1.secondary sexual characteristics 2.reproductive system 3.bone &metabolism 4.cardiovascular 5.brain&nervous system 6.pregnancy related

34. Function of estrogen 1.Reproductive System Ovary & Follicles: Stimulates growth of granulosa cells. Uterus: Proliferation of endometrium (thickening in follicular phase).Increases progesterone receptor expression (preparing for luteal phase). Cervix:Increases cervical mucus volume, makes it thin & watery (spinnbarkeit) → sperm penetration easier. Vagina: Maintains epithelium thickness & glycogen → lactic acid production → acidic pH (protection from infection). Breast: Growth of ductal system (progesterone handles lobulo -alveolar).

35. Function of estrogen 2 Secondary Sexual Characteristics Development of female body contours (breast—growth of stroma and ductile system and fat deposition, wider and round pelvis/ hips, fat distribution).Growth of pubic & axillary hair , skin (smooth & shiny), high pitch voice. 3. Bone & Muscle Increases bone mineralization by inhibiting osteoclast activities . Closure of epiphyseal growth plates at puberty 4. Cardiovascular Improves HDL and lowers LDL (protective against atherosclerosis). Promotes vasodilation via nitric oxide release.

36. Function of estrogen 5.Brain & Nervous SystemModulates mood, memory, and cognitive function .Influences GnRH pulse frequency in hypothalamus → regulating LH/FSH secretion.--- 6. Pregnancy- relatedStimulates uterine blood flow.Helps in breast preparation (ductal growth).Works with progesterone to maintain endometrium. Protein metabolism—anabolic Fat deposition—more in feminine , female wt is lesser than male Electrolyte balance—sodium and water retention

37. Types of estrogen E1 –estrone predominant in menopause –conversion adipose tissue liver & muscle –10 to 60 pg /ml E2— estradiol predominant in reproductive –in ovary –most potent E3—estriol secreted by placenta—weakest T half life time – 1to 2hrs

38. Lab values Day 1to 5 ---20to 80pg/ml Early follicular phase—50 to 150 pg /ml Late follicular phase---> 200 to250 pg /ml Post menopause--- < 20 pg /ml

39. Function of progestrone progesterone is called the “hormone of pregnancy” because its main role is to prepare and maintain the uterus for implantation and pregnancy. It is secreted mainly by the corpus luteum (after ovulation), placenta (in pregnancy), and in small amounts by adrenal gland

40. Function of progestrone 1.Uterus & Menstrual Cycle Converts proliferative endometrium (from estrogen action) into a secretory endometrium → rich in glycogen & nutrients for embryo .Inhibits uterine contractions (relaxing effect, prevents early expulsion of embryo). Cervix—increases cervical thickness Withdrawal of progesterone → triggers menstruation (endometrial shedding).

41. Conti.. 2. Cervix & Vagina --Thickens cervical mucus → forms a mucus plug (blocks sperm & infection after ovulation).Maintains vaginal epithelium. 3. Breast --Stimulates lobulo -alveolar development (milk-secreting units).Works with estrogen (ductal growth from estrogen + alveolar from progesterone).Prepares breast for lactation, but inhibits actual milk secretion after delivery Prolactin—milk secretion Oxytocin—milk ejection Estrogen +progesterone + hPL — prepare prepare Cortisol(casein)+insulin(lactose)+growth hormone+thyroxine (energy)

42. Conti… 4. Pregnancy Maintains uterine lining for implantation.Inhibits maternal immune rejection of fetus .Decreases uterine sensitivity to oxytocin until term. With estrogen , prepares myometrium for labor  near term 5. thermogenic effect –via hypothalamus 6.effect on respiration—increase ventilation via respiratory centre

43. Conti…. 7. Neuroendocrine EffectsModulates GnRH pulse frequency (slows it down).Causes rise in basal body temperature after ovulation (basis of fertility awareness methods).— 9. Other Effects Mild natriuretic effect (via competition with aldosterone).May influence mood and brain activity (often linked to PMS symptoms).

44. Serum progestrone 1.follicular phase <1ng/ml 2.ovulation—2to5ng/ml Luteal phase –5 to 25ng/ml 1 st trimester—11 to 44 ng/ml 2 nd trimester—25 to 83ng/ml 3 rd trimester—58 to 214ng/ml Menopause--< 5ng/ml

45. Conti.. Endogenous progesterone t- life half time –5 mins but circulation it bound to protein globulin(reservoir) and albumin (transport) Synthetic progesterone known as progestins Oral route—5 to 20 mins Vaginal route—6 to 12hrs Injectable route—13 to18 hrs Depot injection—7 to 8 days (premature labour)

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