Reproductive system, adolescence and reproductive health
Male and female systems
Male: testes lie in the scrotum, cooler than the body; seminiferous tubules make sperm and interstitial cells make testosterone; sperm pass through epididymis and vas deferens with seminal vesicle and prostate secretions, out through the urethra. Female: ovaries hold ova, the ovum being the largest human cell; fertilisation normally occurs in the fallopian tube; the zygote implants in the uterus; the placenta exchanges nutrients, oxygen and wastes.
Menstrual cycle
About 28 days: menstruation (days 1–5), follicle growth under FSH, ovulation near day 14, then the corpus luteum secretes progesterone to thicken the lining. Without fertilisation the corpus luteum breaks down and menstruation follows. Irregular cycles are common for one to two years after menarche.
Adolescence
Puberty brings secondary sexual characteristics - in boys a deep voice, facial hair, growth spurt and nocturnal emissions; in girls breast development, menarche and wider hips. Iron, calcium and protein needs rise; acne follows overactive sebaceous glands.
Reproductive health
Menstrual hygiene with clean absorbent pads; accurate information instead of shame; STIs including HIV spread through unprotected sex and infected blood; condoms also protect against infection; legal minimum marriage age is 18 for girls and 21 for boys; the PCPNDT Act bans prenatal sex determination.
Worked example
A 14-year-old has cycles every 40–50 days in her first year. Irregular anovulatory cycles soon after menarche are normal; only persistent very heavy or very painful bleeding needs referral.
Marks-losing traps
Fertilisation occurs in the fallopian tube, not the uterus; the sperm, carrying X or Y, determines the sex of the child; the ovum is released at ovulation, not during menstruation.