PY9.1-10 | Reproductive Physiology — Summary & Reflection

KEY TAKEAWAYS

Reproductive Physiology — Key Takeaways (PY9.1–9.10)

• Sex determination is governed by the SRY gene on the Y chromosome; default development is female. The HPG axis controls all reproductive function through GnRH → FSH/LH → sex steroids.

• Puberty is driven by pulsatile GnRH reactivation; first sign in boys = testicular enlargement; in girls = breast budding. Precocious (<8/9y) and delayed (>13/14y) puberty require investigation.

• Spermatogenesis occurs in seminiferous tubules (FSH + local testosterone essential); takes 74 days; regulated by FSH (via Sertoli/inhibin) and LH (via Leydig/testosterone).

• Testosterone: produced by Leydig cells under LH control; essential for spermatogenesis, secondary sex characteristics, libido, muscle mass, bone density. Negative feedback via hypothalamus + pituitary.

• Ovarian cycle: follicular phase (FSH → Graafian follicle → oestrogen) → LH surge → ovulation → luteal phase (corpus luteum → progesterone). The LH surge is the trigger for ovulation.

• Uterine cycle: menstrual → proliferative (oestrogen) → secretory (progesterone). Progesterone withdrawal = menstruation.

• Contraception targets ovulation (COCP, POP), sperm transport (condoms, IUD), or implantation (IUS). Vasectomy is permanent male contraception with no effect on testosterone.

• Pregnancy: hCG rescues the corpus luteum. Placenta takes over at 12–16 weeks. hCG detected in urine = basis of pregnancy tests.

• Parturition: oxytocin + prostaglandins drive contractions (Ferguson's reflex = positive feedback). Lactation: prolactin (milk synthesis) + oxytocin (let-down reflex).

• Menopause: oestrogen falls, FSH rises markedly, progesterone absent. Oestrogen deficiency → hot flushes, osteoporosis, cardiovascular risk, urogenital atrophy.

• Infertility: male factor (40%), female factor (40%), combined (20%). IVF = ovarian stimulation → egg retrieval → fertilisation in vitro → embryo transfer.

REFLECT

Kolb Reflection — Reproductive Physiology

Take 5 minutes to reflect before closing this guide:

1. Concrete Experience (CE): Think of a patient scenario involving reproductive health you may have encountered — a family member, news story, or case from your Community Medicine or Anatomy classes. What was the presenting problem?

2. Reflective Observation (RO): What did you observe or notice? What did you understand at the time? What do you understand now after this module?

3. Abstract Conceptualisation (AC): Which concept from this module best explains the scenario? (For example: "The irregular periods were due to PCOS — elevated LH:FSH ratio → anovulation → absent corpus luteum → absent progesterone → irregular bleeding.")

4. Active Experimentation (AE): When you next see a patient with infertility, menstrual irregularity, or contraception needs, what history will you take? What investigations will you order first? How has your thinking changed?

There are no right or wrong answers — this is for your personal learning record.