Updated: 12/17/2021

Reproductive Physiology

Review Topic
https://upload.medbullets.com/topic/120200/images/menstrual cycle with hormones.jpg
  • Snapshot
    • A 27-year-old woman presents to her primary care physician due to missed menses. She reports to having a 28-day menstrual cycle with minimal variability, and her last menstrual period was 7 weeks ago. She reports morning sickness and is currently sexually active with one man and use condoms intermittently. Physical examination is unremarkable. A urine β-hCG test is positive. (Pregnancy)
  • Introduction
    • Estrogen
      • source
        • ovaries (17β-estradiol), placenta (estriol), and adipose (estrone)
      • ovarian synthesis
        • theca cells produce androgens secondary to luteinizing hormone (LH) stimulation
          • androgens diffuse to adjacent granulosa cells
        • granulosa cells, under follicle-stimulating hormone (FSH) stimulation, leads to
          • ↑ aromatase activity that results in
            • ↑ conversion of androgens to estrogens (17β-estradiol)
      • function
        • matures and maintains the fallopian tubes, uterus, cervix, and vagina
        • develops secondary sex characteristics
        • breast development
        • maintains pregnancy
          • also decreases uterine threshold to contractile stimuli during pregnancy
        • increases mitotic activity of the endometrium
        • negative and positive feedback effects on FSH and LH secretion
    • Progesterone
      • source
        • corpus luteum, placenta, and adrenal cortex in women
      • function
        • maintains pregnancy
          • increases uterine threshold to contractile stimuli during pregnancy
        • breast development
        • negative feedback on FSH and LH secretion (in luteal phase)
        • uterine secretory activity maintenance in the luteal phase
    • Oogenesis
      • during fetal life 1° oocytes begin meiosis I
        • meiosis I is completed prior to ovulation
          • the oocytes are arrested in prophase I until ovulation occurs
      • oocytes are arrested in metaphase II until the oocyte becomes fertilized
  • Menstrual Cycle
    • Follicular phase (days 1-14)
      • a primordial follicle is formed
      • upregulation of LH and FSH receptors on theca and granulosa cells
        • estrogen results in
          • uterine proliferation
          • negative feedback on anterior pituitary leading to
            • ↓ LH and FSH levels
      • ↓ progesterone levels
    • Ovulation (day 14)
      • ovulation = menses - 14 days
      • secondary to estrogen-induced LH surge
      • cervical mucous is thin, clear, and profuse
        • secondary to ↑ estrogen levels
      • ferning on wet mount due to electrolyte ↑ content
      • anovulation can occur during the first few menstrual cycles due to an immature hypothalamic-pituitary-gonadal axis
    • Luteal phase (days 14-28)
      • development of the corpus luteum which results in
        • estrogen and progesterone synthesis
      • endometrium has ↑ vascularity and secretory activity
      • ↑ basal body temperature due to
        • progesterone's effect on the hypothalamus
      • no fertilization leads to regression of the corpus luteum leading to
        • an abrupt ↓ of estradiol and progesterone
    • Menses (days 0-4)
      • ↓ estradiol and progesterone leads to
        • endometrial sloughing
    • Pathology
      • neonates may experience "menses" secondary to rapid withdrawal of maternal hormones
        • no diagnostic workup or treatment required
      • amenorrhea (primary and secondary)
      • dysmenorrhea
      • abnormal uterine bleeding
  • Pregnancy
    • Fertilization
      • human chorionic gonadotropin (hCG) rescues the corpus luteum from regression which results in
        • continued progesterone secretion
    • Human placental lactogen (HPL)
      • ↑ insulin resistance which results in
        • ↑ glucose and amino acids to the fetus
    • Physiology
      • cardiovascular
        • systolic and diastolic blood pressures (BP) decline
          • there is an ↑ cardiac output and heart rate
        • diastolic murmurs are never normal in pregnancy
      • hematologic
        • dilutional effect on hemoglobin (physiologic anemia) due to
          • increased plasma volume
        • hypercoagulable state
      • pulmonary
        • ↑ tidal volume and minute ventilation that results in
          • a respiratory alkalosis
            • kidneys ↑ bicarbonate loss to compensate
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(M2.GN.17.4752) A 24-year-old woman presents to her physician complaining of intermittent vaginal discharge. She has noticed this for the last 3 months and states that it looks “like egg white”. Although she does not recall a specific pattern to the discharge, she notes that it happens every few weeks or so. She has not noticed a significant odor to the discharge. The patient has regular periods every 28 days with mild cramping and increased fatigue for one day each cycle. Her last period was 2 weeks ago. She has a past medical history of a recent urinary tract infection, for which she received a course of ciprofloxacin. Six months ago, she started having intercourse with a new partner and has not been using barrier protection. At this visit, her temperature is 98.4°F (36.9°C), blood pressure is 124/76 mmHg, pulse is 70/min, and respirations are 14/min. The patient has a soft, nontender abdomen, and speculum exam reveals a clear, thin discharge in the vaginal vault. There is no adnexal or cervical motion tenderness, and the vulvar skin is without erythema or irritation. A wet mount of a vaginal swab is shown in Figure A. Which of the following is the underlying etiology of this patient’s presentation?

QID: 108725

Alteration of vaginal flora



Increased FSH levels



Increased estrogen levels



Sexually transmitted disease



Increased progesterone levels



M 6 D

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