Menstrual cycle

In the syllabus and the exam

The menstrual cycle is studied as the recurring sequence of hormonal and physical changes that prepares the uterus for a possible pregnancy roughly every month, and it is one of the more detail-heavy topics in reproduction and growth because it links directly to hormones such as oestrogen and progesterone. Candidates are commonly asked to describe what happens to the uterine lining across the cycle: it thickens with a rich blood supply in preparation for implantation, and if fertilisation does not take place, this lining breaks down and is expelled as menstrual bleeding, after which the cycle begins again. Exam questions may also test ovulation as the point in the cycle when an ovum is released and is available for fertilisation, since this timing is directly relevant to understanding fertility. A frequent mistake is treating menstruation and the menstrual cycle as the same thing; menstruation is only the bleeding phase, while the menstrual cycle is the entire repeating sequence of events, including the build-up and ovulation phases. Some candidates also incorrectly state that the menstrual cycle stops permanently once fertilisation occurs in a given month, rather than being suspended only for the duration of that particular pregnancy. Some structured questions also ask candidates to relate the thickness of the uterine lining to the level of a named hormone shown on an accompanying graph, so candidates should be able to read such a graph and link a rising or falling hormone level to the corresponding stage of the cycle. This is also why irregularities in the cycle are sometimes used clinically as an early indicator worth investigating further, since a consistently disrupted pattern can reflect an underlying hormonal imbalance rather than a normal variation.

Example

Explaining the reproductive calendar, a candidate writes: 'If fertilisation does not occur, the thickened uterine lining built up during the menstrual cycle breaks down and is shed as menstruation, and the cycle then repeats.'

Related terms

FertilisationPlacentaHormone

Source:SRC-DSKP-EN