(Paper 2) 5.3 Homeostasis: The Reproductive System Flashcards
(36 cards)
What is the menstrual cycle?
A recurring process (~28 days) where the uterus lining builds up in preparation for pregnancy, then is shed if no fertilised egg implants.
What happens if a fertilised egg does not implant into the uterus lining?
The uterus lining is shed – this is called menstruation.
Which four hormones control the menstrual cycle?
FSH, oestrogen, LH, and progesterone.
What does FSH (follicle stimulating hormone) do?
Causes an egg to mature in an ovary and stimulates the ovaries to release oestrogen.
Where is FSH produced?
The pituitary gland.
What are the roles of oestrogen in the menstrual cycle?
Stops FSH production (so only one egg matures)
Repairs and thickens the uterus lining
Stimulates LH release from the pituitary gland
Where is oestrogen produced?
In the ovaries.
What does LH (luteinising hormone) do?
Triggers ovulation – the release of a mature egg from the ovary.
Where is LH produced?
The pituitary gland.
What does progesterone do?
Maintains the uterus lining
Prevents menstruation if pregnancy occurs
Where is progesterone produced?
In the ovaries – and by the placenta during pregnancy.
What is the role of oestrogen in the menstrual cycle?
It repairs and thickens the uterus lining and stimulates LH release.
What happens to oestrogen levels between days 1–12?
Oestrogen gradually increases and peaks around day 12.
What happens to FSH and LH around day 14?
They both peak at ovulation (around day 14), then drop sharply on day 15.
What happens to oestrogen after day 12?
It drops around days 13–14, then has a smaller second peak around day 21.
What happens to progesterone after ovulation?
It increases gradually, peaking around day 21, then decreases again.
What causes ovulation during the menstrual cycle?
A surge in LH, triggered by rising oestrogen levels.
What maintains the uterus lining after ovulation?
Progesterone, produced by the ovaries.
What happens if no fertilisation occurs?
Progesterone and oestrogen levels fall, causing the lining to shed (menstruation).
What hormones are found in the oral contraceptive pill?
Oestrogen and/or progesterone.
How do oral contraceptives prevent pregnancy?
They inhibit FSH production, so eggs cannot mature.
What is the effectiveness of oral contraceptives when taken correctly?
More than 99% effective.
What are some side effects of oral contraceptives?
Changes in weight, mood, and blood pressure.
Why are modern contraceptive pills considered safer than older versions?
They contain lower levels of oestrogen, reducing the risk of side effects.
