The Menstrual Cycle
Four phases across twenty-eight days.
Put the four phases of a 28-day cycle in order. The badge shows the days each phase covers.
Tap the card that comes next
The cycle is counted from the first day of menstruation, so the phase that looks like an ending is actually the start. It begins at menarche, around age 13, and ends at menopause, around 45.
Free play — put the stages in order yourself, then play the whole thing through as one continuous process. Switch to when you're ready to test yourself.
What this lesson covers
Challenges to clear
- Put the four phases in order.
- Lay the ovulatory phase in its correct place.
The task
Put the four phases of a 28-day cycle in order. The badge shows the days each phase covers.
What this lesson covers
- Menstrual phase — The thickened uterine lining breaks down and is shed, along with blood and the unfertilised egg. This lasts about 3 to 5 days and marks day 1 of the cycle.
- Follicular phase — FSH from the pituitary stimulates a follicle in the ovary to grow into a Graafian follicle. The follicle secretes oestrogens, which rebuild and thicken the uterine lining.
- Ovulatory phase — A surge of LH bursts the Graafian follicle and the egg is released into the oviduct. The days around ovulation are the most favourable for conception.
- Luteal phase — The ruptured follicle becomes the corpus luteum and secretes progesterone, which maintains the thickened lining. If the egg is not fertilised the corpus luteum degenerates, progesterone falls, and the lining breaks down — beginning the next cycle.
Hint
The cycle is counted from the first day of menstruation, so the phase that looks like an ending is actually the start. It begins at menarche, around age 13, and ends at menopause, around 45.