Human Reproduction

About this unit

This unit describes how humans reproduce sexually. It covers the male and female reproductive systems, the formation of gametes, the menstrual cycle and its hormonal control, fertilisation, implantation, pregnancy, birth and lactation. Humans are viviparous, with internal fertilisation and internal development, and the unit shows how hormones from the hypothalamus, pituitary and gonads coordinate every step.

Key ideas

• Primary sex organs are the testes and ovaries; accessory ducts and glands support them.
• Spermatogenesis and oogenesis differ in timing and number of functional gametes.
• The menstrual cycle has menstrual, follicular, ovulatory and luteal phases controlled by FSH, LH, oestrogen and progesterone.
• Fertilisation usually occurs in the ampullary region of the fallopian tube.
• The blastocyst implants in the endometrium; the placenta supports the foetus and secretes hormones.
• Parturition is a neuroendocrine reflex; oxytocin plays a key role.

How to prepare

Draw and label the male and female systems, a section of the seminiferous tubule, the ovary and a sperm. Make a timeline of hormone levels across a 28-day cycle. Memorise which hormone comes from which gland and the stages of gametogenesis with ploidy.