1. Menstrual Cycle
Noadswood Science, 2016

2. Menstrual Cycle To explain and describe the menstrual cycle
Monday, May 21, 2018
Menstrual Cycle
To explain and describe the menstrual cycle

3. Precise Learning
Students should be able to describe the roles of hormones in human reproduction, including the menstrual cycle
During puberty reproductive hormones cause secondary sex characteristics to develop
Oestrogen is the main female reproductive hormone produced in the ovary. At puberty eggs begin to mature and one is released approximately every 28 days. This is called ovulation
Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production
Several hormones are involved in the menstrual cycle of a woman.
Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary.
Luteinising hormone (LH) stimulates the release of the egg.
Oestrogen and progesterone are involved in maintaining the uterus lining
Students should be able to explain the interactions of FSH, oestrogen, LH and progesterone, in the control of the menstrual cycle (higher tier only)
Students should be able to extract and interpret data from graphs showing hormone levels during the menstrual cycle (higher tier only)

4. Hormones Hormones are chemicals secreted by glands in the body
Different hormones affect different target organs, with the bloodstream transporting hormones from the glands to the target organs…

5. Hormones Gland Hormone Target Organs Effect Adrenal gland Adrenalin
Liver & heart
Prepares body (“flight or fight”)
Ovary
Oestrogen
Ovaries, uterus, pituitary gland
Controls puberty and the menstrual cycle in females; stimulates production of LH and suppresses the production of FSH in the pituitary gland
Progesterone
Uterus
Maintains the lining of the womb - suppresses FSH production in the pituitary gland
Pancreas
Insulin
Liver
Controls blood sugar levels
Pituitary gland
Anti-diuretic hormone (ADH)
Kidney
Controls blood water level by triggering uptake of water in kidneys
Luteinising hormone (LH)
Ovaries
Triggers egg release and progesterone production in ovaries
follicle stimulating hormone (FSH)
Triggers egg ripening and oestrogen production in ovaries
Testes
Testosterone
Male reproductive organs
Controls puberty in males

6. Puberty
At puberty the body starts releasing sex hormones that trigger off secondary sexual characteristics (facial hair in men / breasts in women etc…) and causing egg maturation in women
In men the main reproductive hormone is testosterone (produced by the testes)
In women the main reproductive hormone is oestrogen (produced by the ovaries)

7. Menstrual Cycle
The menstrual cycle in women is a recurring process in which the lining of the uterus (womb) is prepared for pregnancy, and if pregnancy does not happen, the lining is shed at menstruation
Several hormones control this cycle, which includes controlling the release of an egg each month from an ovary, and changing the thickness of the uterus lining
These hormones are secreted by the ovaries and pituitary gland

8. Menstrual Cycle
The menstrual cycle begins at day 1, when bleeding from the vagina begins. This is caused by the loss of the uterus lining (with some blood) - this is known as menstruation, or having a period (lasting 3-7 days)
By around day 5 menstruation stops. The lining of the uterus begins to re-grow, and an egg cell starts to mature in one of the ovaries
Around day 14 the mature egg cell is released from the ovary. This is called ovulation - the egg cell travels down the oviduct towards the uterus

9. Menstrual Cycle
If the egg cell does not meet with a sperm cell (no fertilisation) then the lining of the uterus begins to break down again, and the cycle repeats
BUT - if the egg cell meets and joins with a sperm cell (fertilisation) then it attaches to the lining of the uterus and the female becomes pregnant - at this point the cycle stops

10. Menstrual Cycle
Day 1 - menstrual cycle and menstruation (period) begins (lasts 3-7 days) Day menstruation (period) stops Day 14 - an egg cell is released from one of the ovaries (ovulation) Day 28 - if the egg has not been fertilised (by a sperm), the cycle repeats

11. Menstrual Cycle
Complete the menstrual cycle worksheet, sticking all the sections into your book

12. Menstrual Cycle
Menstruation (period)
Uterus lining breaks apart without progesterone
Most fertile time
The egg cell is swept along the oviduct towards the uterus
Egg maturation
FSH released – egg cell starts to mature in ovary and the uterus lining builds up
Ovulation
The egg cell is released from the ovary – caused by LH
If an egg is fertilised between days 15-28, the menstrual cycle will stop
Fertile means the female has the ability to become pregnant (greatest chance of conception)
Probably ~ 28 days later: 4th December (although this can be a few days before / after)

13. FSH
The hormone FSH (follicle stimulating hormone) is secreted by the pituitary gland
FSH makes two things happen: -
It causes an egg to mature in an ovary
It stimulates the ovaries to release the hormone oestrogen

14. Oestrogen The hormone oestrogen is secreted by the ovaries
Oestrogen makes two things happen: -
It stops FSH being produced - so that only one egg matures in a cycle
It stimulates the pituitary gland to release the hormone LH

15. LH
The hormone LH (luteinising hormone) causes the mature egg to be released from the ovary
Knowing when LH has surged can be useful when trying to conceive as this informs you of when ovulation has occurred

16. Progesterone
Progesterone is secreted by ovaries, maintaining the lining of the uterus (levels stay high during pregnancy)

17. Menstrual Cycle

18. Hormone Interaction
The levels of the four hormones fluctuate throughout the cycle and interact with each other to promote or inhibit the release of other hormones…
Higher Tier

19. Practice Questions
What effect does FSH have on an egg in the menstrual cycle?
What is the function of LH?
The graph show the level of a hormone measured in the bloodstream of a woman during her 28 day menstrual cycle
Which hormone is shown on the graph and where is this hormone produced?

20. Answers
What effect does FSH have on an egg in the menstrual cycle – it causes and egg to mature
What is the function of LH – stimulates the release of an egg (14)
The graph show the level of a hormone measured in the bloodstream of a woman during her 28 day menstrual cycle
Which hormone is shown on the graph and where is this hormone produced – LH (stimulates the egg) and is produced in the pituitary gland