The menstrual cycle

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Lesson notes

Overview of the Menstrual Cycle

The **menstrual cycle** is a monthly process that prepares the female body for pregnancy.
It typically lasts around **28 days**, but can vary from person to person.
The cycle involves the release of an egg, preparation of the uterus, and shedding of the lining if no pregnancy occurs.

Stage 1: Menstruation (Days 1–5)

Also known as a **period**.
The lining of the uterus breaks down and is shed from the body through the vagina.
Menstruation usually lasts between **3 to 7 days**.

Stage 2: Uterus Lining Builds Up

The body prepares to release an egg from the ovary.
The hormone **oestrogen** helps to thicken the uterus lining ready for a possible pregnancy.

Stage 3: Ovulation (Around Day 14)

**Ovulation** usually happens around the middle of the cycle (day 14).
The ovary releases an egg.
The egg travels down the **fallopian tube**.
This is the time when a woman is **most fertile**.

Stage 4: Uterus Lining Thickens and Is Maintained

After ovulation, the body produces the hormone **progesterone**.
Progesterone makes the lining of the uterus even thicker.
If the egg is not fertilised, the uterus lining breaks down and the cycle restarts with menstruation.

Key Hormones

**Oestrogen**: helps thicken the uterus lining before ovulation.
**Progesterone**: maintains and further thickens the uterus lining after ovulation.

The four stages of the menstrual cycle: menstruation, lining build-up, ovulation, and lining maintenance.

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Practice questions

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1.What happens in the first five days of the menstrual cycle?
Medium
- AThe uterus lining builds up
- BThe uterus lining breaks down and is shed (menstruation)
- CThe ovary releases an egg (ovulation)
- DThe uterus lining thickens further
2.On which day of the menstrual cycle does ovulation usually happen?
Easy
- ADay 1
- BDay 7
- CDay 14
- DDay 28
3.What is ovulation?
Medium
- AThe breakdown of the uterus lining
- BThe release of an egg from an ovary
- CThe thickening of the uterus lining
- DThe shedding of the uterus lining
4.What happens to the uterus lining if an egg is not fertilised?
Medium
- AIt stays thick and is maintained
- BIt breaks down and is shed
- CIt continues to thicken
- DIt is reabsorbed by the body
5.What is the role of oestrogen in the menstrual cycle?
Medium
- AIt causes ovulation
- BIt thickens the uterus lining
- CIt maintains the uterus lining after ovulation
- DIt breaks down the uterus lining
6.What is the role of progesterone in the menstrual cycle?
Medium
- AIt causes the release of an egg
- BIt thickens the uterus lining before ovulation
- CIt makes the uterus lining even thicker and maintains it after ovulation
- DIt triggers menstruation
7.During which stage of the menstrual cycle is a woman most fertile?
Hard
- ADuring menstruation
- BJust after menstruation
- CAt ovulation
- DJust before menstruation
8.Which hormone is primarily responsible for maintaining the uterus lining after ovulation?
Hard
- AOestrogen
- BProgesterone
- CFSH
- DLH

More questions

9.If the menstrual cycle is 28 days and ovulation occurs on day 14, on which day would menstruation begin if fertilisation does not occur?
Hard
- ADay 1
- BDay 14
- CDay 21
- DDay 28
10.The graph below shows the thickness of the uterus lining over a 28-day menstrual cycle. On which day does ovulation most likely occur? (Assume day 1 is the start of menstruation.)
Medium
- ADay 14
- BDay 5
- CDay 21
- DDay 28
11.A woman has a menstrual cycle that lasts 32 days. If ovulation occurs 14 days before the end of the cycle, on which day does ovulation occur?
Hard
- ADay 18
- BDay 14
- CDay 16
- DDay 20
12.During which stage of the menstrual cycle does the uterus lining break down and leave the body?
Easy
- AMenstruation
- BOvulation
- CLining build-up
- DLining maintenance
13.Which hormone is primarily responsible for thickening the uterus lining before ovulation?
Medium
- AOestrogen
- BProgesterone
- CFSH
- DLH
14.The table shows the levels of two hormones (A and B) during the menstrual cycle. Which combination correctly identifies the hormones?
Medium
- AA = oestrogen, B = progesterone
- BA = progesterone, B = oestrogen
- CA = FSH, B = LH
- DA = LH, B = FSH
15.A clinical trial studies a new contraceptive pill that keeps progesterone levels high throughout the cycle. What effect would this have on the menstrual cycle?
Hard
- AThe uterus lining would be maintained and menstruation would not occur
- BOvulation would be stimulated
- CThe uterus lining would thicken and then break down immediately
- DMenstruation would occur earlier than usual
16.What is the typical length of the menstrual cycle?
Easy
- A28 days
- B14 days
- C21 days
- D35 days
17.The diagram shows the female reproductive system. Which part releases the egg during ovulation?
Medium
- AOvary
- BFallopian tube
- CUterus
- DCervix
18.A researcher measures the thickness of the uterus lining (mm) on different days of a 28-day cycle: day 1: 2 mm, day 7: 4 mm, day 14: 8 mm, day 21: 12 mm, day 28: 2 mm. What is the percentage increase in thickness from day 1 to day 21?
Hard
- A500%
- B600%
- C400%
- D300%
19.In a fertility treatment, a woman is given injections of oestrogen early in her cycle. What is the likely effect on the uterus lining?
Medium
- AIt will thicken more quickly than normal
- BIt will break down immediately
- CIt will remain thin
- DIt will not change
20.After ovulation, which hormone helps to maintain the uterus lining?
Easy
- AProgesterone
- BOestrogen
- CTestosterone
- DAdrenaline
21.A study compares the menstrual cycles of two groups: Group A has an average cycle length of 28 days, Group B has an average of 35 days. Assuming ovulation occurs 14 days before the end of the cycle, on which day does ovulation occur in Group B?
Hard
- ADay 21
- BDay 14
- CDay 28
- DDay 35
22.A scientist wants to investigate the effect of a hormone on the thickness of the uterus lining in mice. Which experimental design would provide the most reliable evidence?
Medium
- AGive all mice the hormone and measure lining thickness after one cycle.
- BGive half the mice the hormone and half a placebo, then compare lining thickness after one cycle.
- CGive mice the hormone and measure lining thickness daily for one cycle.
- DUse mice that naturally have different hormone levels and measure lining thickness.
23.In an experiment, a group of women tracked their basal body temperature (BBT) daily. The BBT rises slightly after ovulation due to increased progesterone. If a woman's BBT rises on day 16 of a 28-day cycle, which statement is most likely correct?
Hard
- AOvulation occurred on day 14.
- BOvulation occurred on day 16.
- COvulation occurred on day 18.
- DOvulation occurred on day 12.
24.Which hormone is responsible for thickening the uterus lining before ovulation?
Easy
- AProgesterone
- BOestrogen
- CLuteinising hormone
- DFollicle-stimulating hormone
25.A woman has a 35-day menstrual cycle. Assuming ovulation occurs 14 days before the end of the cycle, on which day does ovulation occur?
Medium
- ADay 14
- BDay 21
- CDay 28
- DDay 35
26.A student measures the thickness of the uterus lining (in mm) on different days of a 28-day cycle: day 1: 2 mm, day 7: 4 mm, day 14: 8 mm, day 21: 12 mm, day 28: 2 mm. Which conclusion is supported by the data?
Hard
- AOvulation occurred around day 14.
- BThe lining is thickest just before menstruation.
- CProgesterone is highest on day 7.
- DOestrogen peaks on day 21.
27.A new contraceptive pill contains a high dose of progesterone. What effect does this have on the menstrual cycle?
Medium
- AIt stimulates ovulation.
- BIt prevents the uterus lining from thickening.
- CIt causes the uterus lining to thicken and be maintained, preventing menstruation.
- DIt increases oestrogen production.
28.A graph shows the levels of oestrogen and progesterone over a 28-day cycle. Oestrogen peaks around day 13, and progesterone peaks around day 21. Which statement is correct?
Hard
- AOvulation occurs when progesterone is highest.
- BOvulation occurs after the oestrogen peak.
- COvulation occurs before the oestrogen peak.
- DOvulation occurs when both hormones are at their lowest.
29.Which stage of the menstrual cycle is a woman most fertile?
Medium
- ADuring menstruation
- BJust before ovulation
- CJust after ovulation
- DDuring the build-up of the uterus lining
30.The menstrual cycle typically lasts around how many days?
Easy
- A14 days
- B21 days
- C28 days
- D35 days
31.A scientist measures the length of the menstrual cycle in 100 women and finds an average of 29 days with a standard deviation of 3 days. Which statement is most accurate?
Medium
- AAll women have a 29-day cycle.
- BMost women have cycles between 26 and 32 days.
- CThe shortest cycle is 26 days.
- DThe longest cycle is 32 days.
32.In an experiment, researchers measure the concentration of oestrogen and progesterone in blood samples from women at different stages of the menstrual cycle. They find that oestrogen is high on day 12, and progesterone is high on day 22. If a woman has a cycle length of 30 days, on which day is she most likely to ovulate?
Hard
- ADay 12
- BDay 14
- CDay 16
- DDay 22
33.Ovulation usually occurs around which day of a 28-day menstrual cycle?
Easy
- ADay 14
- BDay 1
- CDay 21
- DDay 7
34.During menstruation, what is shed from the body?
Medium
- AThe lining of the uterus
- BAn unfertilised egg
- CThe ovary
- DThe fallopian tube
35.If a woman has a 35-day menstrual cycle and ovulation occurs 14 days before the end of the cycle, on which day does ovulation occur?
Hard
- ADay 21
- BDay 14
- CDay 28
- DDay 7
36.Which of the following statements about the menstrual cycle is true?
Medium
- AThe menstrual cycle typically lasts 28 days but can vary.
- BOvulation always occurs on day 14.
- CMenstruation lasts exactly 5 days.
- DProgesterone is only produced before ovulation.
37.A researcher measures the thickness of the uterus lining (mm) on different days of a 28-day cycle: day 1: 2 mm, day 7: 4 mm, day 14: 8 mm, day 21: 12 mm, day 28: 2 mm. On which day does ovulation most likely occur?
Hard
- ADay 14
- BDay 7
- CDay 21
- DDay 28
38.Which hormone is responsible for maintaining the uterus lining after ovulation?
Medium
- AProgesterone
- BOestrogen
- CFSH
- DLH
39.A woman has a 30-day menstrual cycle. If ovulation occurs 14 days before the end of the cycle, on which day does ovulation occur?
Medium
- ADay 14
- BDay 16
- CDay 15
- DDay 13
40.A scientist measures the concentration of oestrogen and progesterone in blood samples from women at different stages of the menstrual cycle. The results show that oestrogen peaks around day 13 and progesterone peaks around day 21. Which statement best explains these observations?
Medium
- AOestrogen peaks just before ovulation to stimulate the release of an egg, while progesterone peaks after ovulation to maintain the uterus lining.
- BProgesterone peaks just before ovulation to stimulate the release of an egg, while oestrogen peaks after ovulation to maintain the uterus lining.
- CBoth hormones peak at the same time to prepare the uterus for pregnancy.
- DOestrogen is high only during menstruation, and progesterone is high only during ovulation.

Revision notes

## The Menstrual Cycle The menstrual cycle is a monthly process (~28 days) that prepares the female body for pregnancy. It involves the release of an egg from the ovaries, preparation of the uterus for pregnancy, and shedding of the uterus lining if pregnancy does not occur. ### Four Stages 1. **Menstruation (days 1-5)**: The uterus lining breaks down and is shed from the body through the vagina (a period). Usually lasts 3–7 days. 2. **Uterus lining builds up**: The hormone **oestrogen** helps thicken the uterus lining to prepare for a possible pregnancy. 3. **Ovulation (day 14)**: The ovary releases an egg. The egg travels down the fallopian tube. This is when a woman is most fertile. 4. **Uterus lining thickens and is maintained**: After ovulation, the hormone **progesterone** makes the lining even thicker. If the egg is not fertilised, the lining breaks down and the cycle starts again with menstruation. ### Key Points - Ovulation = release of an egg from the ovary. - A woman is most fertile during ovulation. - If the egg isn't fertilised, the uterus lining breaks down. ### Hormones - **Oestrogen**: Thickens the uterus lining. - **Progesterone**: Makes the uterus lining even thicker after ovulation.

Menstrual cycle: A monthly process that prepares the female body for pregnancy, typically lasting around 28 days.
Menstruation: The first stage of the menstrual cycle (days 1-5) when the lining of the uterus breaks down and is shed from the body through the vagina.
Ovulation: The release of an egg from the ovary, usually around day 14 of the menstrual cycle.
Oestrogen: A hormone that helps to thicken the uterus lining to get ready for a possible pregnancy.
Progesterone: A hormone produced after the egg is released that makes the lining of the uterus even thicker.

Flashcards

What is the menstrual cycle?

A monthly process that prepares the female body for pregnancy, typically lasting around 28 days.

What are the four stages of the menstrual cycle?

Menstruation, uterus lining builds up, ovulation, and uterus lining thickens and is maintained.

What happens during menstruation?

The lining of the uterus breaks down and is shed from the body through the vagina; it usually lasts 3 to 7 days.

Which days of the menstrual cycle are menstruation?

Days 1-5.

What hormone helps to thicken the uterus lining?

Oestrogen.

What is ovulation?

The release of an egg from the ovary, usually around day 14 of the cycle.

When does ovulation usually occur?

Around day 14, the middle of the cycle.

When is a woman most fertile?

Around the time of ovulation, when the egg is released.

What hormone is produced after ovulation?

Progesterone.

What is the role of progesterone?

It makes the lining of the uterus even thicker to prepare for pregnancy.

What happens if an egg is not fertilised?

The uterus lining breaks down and the cycle starts again with menstruation.

What is the typical length of the menstrual cycle?

Around 28 days, but it can vary.

True or false: Ovulation is when an ovary releases an egg.

True.

True or false: A woman is most fertile before she ovulates.

False. She is most fertile around ovulation.

Describe what happens in the first five days of the menstrual cycle.

Menstruation occurs: the uterus lining breaks down and is shed through the vagina.

What is the role of oestrogen in the menstrual cycle?

It helps to thicken the uterus lining to get ready for a possible pregnancy.

After ovulation, what happens to the uterus lining?

Progesterone makes it even thicker and maintains it.

Where does the egg travel after ovulation?

Down the fallopian tube.

What triggers the start of a new menstrual cycle?

If the egg is not fertilised, the uterus lining breaks down and menstruation begins.

How long does menstruation usually last?

3 to 7 days.

What is the purpose of the menstrual cycle?

To prepare the female body for pregnancy.

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