The male and female reproductive systems, the hormones oestrogen and progesterone in the menstrual cycle, the role of FSH and LH, and how hormones are used in contraception and fertility treatment such as IVF.

What this dot point is asking

CCEA wants you to describe the male and female reproductive systems, explain the roles of oestrogen and progesterone in the menstrual cycle, describe the roles of FSH and LH, and explain how hormones are used in contraception and fertility treatment such as IVF.

The reproductive systems

Hormones of the menstrual cycle

Hormones in contraception and fertility

The contraceptive pill contains hormones that stop FSH, so no egg matures and ovulation is prevented, meaning no pregnancy. Fertility treatments do the opposite: FSH and LH can be given to stimulate eggs to mature, and in IVF (in vitro fertilisation) eggs are collected, fertilised outside the body, and an embryo is placed in the uterus.

Examples in context

Example 1. Why progesterone falling triggers a period

During the second half of the cycle, progesterone keeps the uterus lining thick, ready for a fertilised egg. If the egg is not fertilised, the ovary stops making progesterone, so its level falls. Without progesterone the lining can no longer be maintained, so it breaks down and is lost as a period. This shows how a falling hormone level, not a rising one, can be the signal that starts a process, a subtle point CCEA likes to test.

Example 2. Helping a couple who cannot conceive

If a woman does not release eggs because she makes too little FSH, doctors can give her FSH and LH as a fertility drug to stimulate her ovaries to mature and release eggs. If the oviducts are blocked, IVF can be used: eggs are collected, fertilised with sperm in the laboratory, and an embryo is returned to the uterus. These treatments apply the same hormones that control the natural cycle, showing how understanding the menstrual cycle leads directly to medical uses.

Example 3. Reading a menstrual-cycle graph

CCEA often shows a graph of the four hormone levels across the cycle and asks you to link them. Early in the cycle FSH rises and stimulates an egg to mature, and oestrogen rises as the lining builds up. Oestrogen peaks just before the middle of the cycle, triggering a surge of LH that causes ovulation around day 14. After ovulation, progesterone rises and holds the lining in place. If the egg is not fertilised, progesterone and oestrogen fall, the lining is lost, and the cycle restarts. Being able to match each rise and fall to its hormone, and to say which hormone causes which event, is one of the most common Unit 2 hormone questions, so practise tracing the four lines in order.

Try this

Q1. Which hormone triggers ovulation? [1 mark]

• Cue. LH (luteinising hormone).

Q2. How does the contraceptive pill prevent ovulation? [2 marks]

• Cue. Its hormones stop FSH being released, so no egg matures or is released.