The menstrual cycle occurs monthly and is controlled by hormones from the pituitary gland that signal the ovaries to release an egg (ova) through the fallopian tubes to the uterus. If the egg is not fertilized by a sperm, it disintegrates and the uterine lining breaks down and is passed, along with blood and tissue, through menstruation or a period. The four stages of the menstrual cycle are: bleeding starts on day 1 when the uterine lining breaks down; rebuilding of the lining starts on day 4; an egg is released around day 14 and can be fertilized for 3 days; and the thickened lining remains on day 28 awaiting a fertilized egg before breaking down again if none arrives.

1. The menstrual cycle
• Target
• To know the menstrual cycle and why it
takes place.

3. Hormone
release
• Hormones produced in
the pituitary gland in
the brain send signals
to the ovaries to
release an ova about
once per month.
• The ova travels down
the fallopian tube to the
womb where it may be
fertilized by a sperm.

4. There are three hormones controlling the ova – one
causes the egg to mature the other causes the egg to be
released. A third hormone oestrogen inhibits further eggs
from becoming mature.
Egg
stimulated to
mature
Oestrogen stops
stimulation and
starts release.
Egg stimulated
to be released

5. The ova
• This picture shows an
ova being released –
magnified 2130 times
larger than it is in real
life.

6. Menstruation
• This is the process
women go through
every month to allow
the body to prepare
to have a baby.
• If the ova is not
fertilised it comes
away during a
‘period’.
• If it is fertilised the
baby starts to grow.

9. The Menstrual Cycle

10. The FOUR stages of the menstrual cycle:
Day 1: Bleeding starts when the lining of the uterus breaks down
and passes out the vagina – “Having a period”
Day 4: The lining starts to build up again and thickens into a spongy
layer of blood cells
Day 14 (approx): An egg is released and lasts for around 3 days
Day 28: The lining stays thick awaiting the arrival of a fertilised
egg. If one doesn’t come then the lining breaks down again.

11. Questions
1. What do we call the monthly cycle?
2. When does this cycle start?
3. When does this cycle stop?
4. What does the uterus do in this cycle?
5. What do we call it when the uterus
lining breaks down?
6. What is another name for periods?

12. • Menstrual cycle
• Puberty
• Menopause
• Thickens
• Period
• menstruation