The menstrual cycle Flashcards
How long is the menstrual cycle?
About 28 days
What are the stages of the menstrual cycle?
- Uterine lining thickens
+ eggs mature - Eggs finish maturing and release from ovary
+ Uterine lining stays thick - If egg is fertilised pregnancy takes place
+ If egg isn’t fertilised uterine lining and egg are shed
How many main stages are there in the menstrual cycle?
3
What happens in the first stage? (detail)
- Start of cycle
- The lining of the uterus (womb) thickens, ready to support a developing baby.
- Eggs start maturing in the follicles of the ovary.
What happens in the second stage? (detail)
- About 14 days after the start of the cycle:
- Egg is released from ovary in ovulation.
- Uterus lining stays thick for several days after egg release.
What happen in the third stage? (detail)
- If the egg is fertilised by sperm, pregnancy takes place:
- The lining of the uterus would provide protection and food for the developing embryo.
- If the egg is not fertilised, about 14 days after ovulation:
- The uterus lining and egg are shed.
- This is the period.
What gland controls the release of the hormones?
The pituitary gland
Where is the pituitary gland?
The brain
What 4 hormones are involved in the menstrual cycle?
- Oestrogen
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Progesterone
What is oestrogen?
- Comes from ovaries in response to FSH.
- Female sex hormone.
- Stimulates uterus lining to grow again after menstruation in preparation for pregnancy.
- Inhibits FSH.
- Stimulates LH.
What is FSH?
- Follicle stimulating hormone.
- Comes from pituitary gland.
- Makes eggs mature in the ovaries.
- Stimulates ovaries to produce hormones like oestrogen.
What is LH?
- Luteinising hormone.
- Comes from pituitary gland.
- Stimulates the release of a mature egg from ovary.
- Levels fall after ovulation.
What is progesterone?
- Comes from the empty egg follicle in the ovary after ovulation.
- Helps maintain a pregnancy if egg is fertilised.
- Inhibits FSH and LH.
- Maintains uterus lining so it can receive an embryo if the egg is fertilised.
How does the egg change throughout the cycle?
- Egg matures up to about day 14.
- At abou day 14, ovulation begins.
- After about day 20, yellow body forms around the egg.
- After about day 21, yellow body breaks down.
- Egg is released during the period.
What are the pituitary hormones?
- FSH
- LH
What happens to the levels of FSH during the menstrual cycle?
- Increases after the period, decreasing after the uterus lining has thickened.
- Slightly increases during ovulation then decreases straight after.
What happens to the levels of LH during the menstrual cycle?
- Stays low then rapidly spikes during ovulation.
What happens to the levels of oestrogen during the menstrual cycle?
- Slowly increases as uterus lining builds up.
- Suddenly drops after ovulation starts.
- Slowly increases after ovulation ends.
- Drops off when period starts.
What happens to the levels of progesterone during the menstrual cycle?
- Slowly increases after ovulation.
- Decreases and flatlines as period starts.
What happens to the levels of uterus lining during the menstrual cycle?
- Is thin at the start of the cycle.
- Slowly thickens from days 5 to 14.
- Gets more blood after ovulation.
- Remains thick until period starts.
- Gets thin again as it is released during period.
