To overcome fertility problems in males or females
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What are the four stages of IVF?
Down regulation; Artificial doses of hormones; Egg retrieval and fertilisation; Establishing a pregnancy
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What happens in the down-regulation stage of IVF?
The woman takes a drug each day (nasal spray) to stop pituitary gland secreting FSH and LH. This indirectly stops progesterone and estrogen secretion. Suspends normal menstrual cycle to allow control of timing and egg production
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What is the second stage of IVF?
Daily intramuscular injections of FSH and LH are injected for 10 days to stimulate follicle development
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What is superovulation?
The FSH injections for IVF are at a much higher dosage than the normal menstrual cycle so multiple follicles develop at once
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How many follicles can you expect to develop in superovulation?
12-20
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What size must the follicles be before another injection is given?
18mm diameter
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What does an injection of hCG do?
Stimulates follicles to mature
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How do they get the eggs out in IVF?
A micropipette mounted on an ultrasound scanner is passed through the uterus wall to wash eggs out of follicles
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How many sperm cells are the eggs mixed with?
50,000-100,000
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Where and how long does 'fertilisation' take place for?
In a shallow petri dish at 37 degrees celsius until the next day
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At what age are the embryos implanted into the mother?
48 hours
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Why does the woman require a progesterone tablet after implantation?
She has not undergone a menstrual cycle so to keep the uterus lining maintained
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Where is a progesterone tablet placed?
In the vagina
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What was William Harvey taught about reproduction?
The 'soil and the seed' method whereby the male produces a seed that develops into an egg when mixed with menstrual blood and the egg develops into a fetus inside the mother
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How did Harvey test Aristotle's theory?
Dissected and examined slaughtered female deer during the mating season
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When is the deer mating season?
Autumn
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What did Harvey expect to find in his experiment?
Eggs developing in the uterus immediately after mating
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What did Harvey actually find?
Eggs developing in the uterus two or more months after the start of the mating season
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What did Harvey conclude?
Aristotle's theory of reproduction is false but offspring do not derive from mating
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Why did Harvey devise an evidently false idea about reproduction?
Development of gametes, fertilisation and early stages of embryo development can only be seen with an effective microscope which was not invented until after his death
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Why was Harvey unlucky in his choice of deer?
The embryos remain particularly small for an unusually long period of time
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What can we learn about science discoveries in general from the Harvey experiment?
Research has often been hampered by deficiencies in apparatus with discoveries only being made as improvements in technology do
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What are some reasons supporting IVF?
Men can continue to have kids older so why not women?; allows better family planning; helps couples suffering from infertility; on the NHS so is not expensive
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What are some reasons against IVF?
We shouldn't meddle with nature and our bodies; Killing left over embryos is killing human life; people could mistake a parent for a grandparent; Isn't helping people already in this world more important than creating it?; Already a population issue
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Other cards in this set
Card 2
Front
What are the four stages of IVF?
Back
Down regulation; Artificial doses of hormones; Egg retrieval and fertilisation; Establishing a pregnancy
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