Reproduction: MDCAT Notes and MCQs
Male reproductive system
- Testes lie in the scrotum (2–3 °C below body temperature, needed for spermatogenesis).
- Seminiferous tubules produce sperm; Sertoli cells nourish developing sperm; interstitial (Leydig) cells secrete testosterone.
- Pathway: seminiferous tubules → epididymis (storage & maturation) → vas deferens → ejaculatory duct → urethra.
- Accessory glands: seminal vesicles (fructose-rich fluid, ≈ 60% of semen), prostate (alkaline fluid), Cowper's/bulbourethral glands (mucus).
- Hormones: GnRH (hypothalamus) → FSH (stimulates spermatogenesis via Sertoli cells) and LH/ICSH (stimulates testosterone secretion).
Female reproductive system
- Ovaries: produce ova and hormones (oestrogen, progesterone). Oviduct (Fallopian tube): site of fertilization. Uterus: implantation and development; inner lining = endometrium. Cervix, vagina.
Menstrual cycle (≈ 28 days)
| Phase | Days | Events / hormones |
|---|---|---|
| Menstrual | 1–5 | Endometrium sheds (fall in progesterone & oestrogen) |
| Follicular (proliferative) | 6–13 | FSH → Graafian follicle develops → secretes oestrogen → endometrium repairs and thickens |
| Ovulation | ≈ 14 | High oestrogen triggers LH surge → follicle ruptures, secondary oocyte released |
| Luteal (secretory) | 15–28 | LH → corpus luteum → progesterone (+ oestrogen) maintains endometrium; inhibits FSH/LH. No fertilization → corpus luteum degenerates → menstruation |
If pregnancy occurs, hCG from the embryo maintains the corpus luteum (basis of pregnancy tests). Menopause ≈ 45–50 years.
Sexually transmitted diseases
| Disease | Causative agent | Main symptoms |
|---|---|---|
| Gonorrhoea | Neisseria gonorrhoeae (bacterium) | Painful urination, pus discharge; can cause sterility |
| Syphilis | Treponema pallidum (spirochaete) | Painless sore (chancre) → rash → late damage to heart, brain |
| Genital herpes | Herpes simplex virus (HSV-2) | Painful blisters/ulcers; recurrent |
| Chlamydia | Chlamydia trachomatis | Often silent; discharge, pelvic inflammatory disease |
| AIDS | HIV (retrovirus) | Immune failure, opportunistic infections |
PMDC learning outcomes for this unit
- Human Reproductive system: 8.1 Describe the functions of various parts of the male & female reproductive systems and the hormones that regulate those functions
- Menstrual cycle: 8.2 Describe the menstrual cycle (female reproductive cycle) emphasizing the role of hormones
- Sexually transmitted diseases: 8.3 List the common sexually transmitted diseases along with their causative agents and main symptoms