B5g: Life Goes On

 Humans, like all other animals, have basic needs for survival and reproduction to carry on our species. When things do not work as they should we expect modern techniques to solve our problem. Sometimes solutions raise other issues.

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What is the function of the scrotum?
Keeps the testes outside the body where the temperature is better for sperm development.
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Describe the three main stages of the menstrual cycle.
Menstruation – uterus lining breaks down (period), thickening of uterus lining and ovulation – egg released by ovary.
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Is fertilisation and pregnancy guaranteed to all couples?
No
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Give three causes of infertility.
Blockage of fallopian tubes or sperm ducts, eggs not developed or released from ovaries and insufficient fertile sperm produced by testes.
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In some - not all - cases of infertility, how can pregnancy be achieved?
By fertility treatment.
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What are the reasons for checking foetal development?
To identify the risk of genetic disorders, e.g. down's syndrome and cystic fibrosis.
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What are the two human endocrine glands? What hormone(s) is/are produced there?
Ovaries – oestrogen, progesterone and testes – testosterone.
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What four hormones are involved in the menstrual cycle?
Progesterone, Oestrogen, LH and FSH
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What is the role of progesterone in the menstrual cycle?
progesterone maintains the uterus wall.
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What is the role of oestrogen in the menstrual cycle?
oestrogen causes the repair of the uterus wall.
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What is the role of LH in the menstrual cycle?
LH (luteinising hormone) controls ovulation.
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What is the role of FSH in the menstrual cycle?
FSH (follicle-stimulating hormone) stimulates an egg to develop.
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Where is FSH and LH produced and released?
By the pituitary gland in the brain.
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Name six possible treatments for infertility.
Surrogacy, artificial insemination, use of FSH, “in vitro” fertilisation (IVF), egg donation and ovary transplants.
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Describe the treatment for infertility: egg donation
Some woman can't produce eggs but can still have a baby by donated eggs.
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Describe the treatment for infertility: use of FSH
Some women have very low levels of the hormone FSH, so their eggs don't develop properly and they cant get pregnant. FSH injections can increase fertility by simulating egg production - making fertilisation more likely.
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Describe the treatment for infertility: artificial insemination
A man's sperm is placed into a woman's uterus without having sex. It's used if there's some kind of problem with the sperm reaching the egg, or if the man suffers from certain kinds of infertility. Sperm donor can also be used in necessary.
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Describe the treatment for infertility: IVF
A woman's eggs are fertilised outside of the body. The woman is given hormones to stimulate egg production. Several eggs are then collected and mixed with the man's sperm, and a few fertilised eggs are implanted back into the mother's uterus.
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Describe the treatment for infertility: surrogacy
Some women can produce eggs but miscarry. The couple's fertilised eggs can be implanted into another woman (called a surrogate mother), who gives birth to their baby.
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Describe the treatment for infertility: ovary transplants
Some women don't have ovaries (e.g. due to surgery for ovarian cancer) or they have damaged ones that don't produce any eggs (e.g. often due to cancer treatment). A relatively new (and rare) way to treat this is to transplant a healthy ovary donated
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An advantage of fertility treatments
They give an infertile couple a child
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Two disadvantages of fertility treatments
In IVF not all the fertilised eggs are implanted back.Some think that throwing away extra fertile eggs is denying a life&morally wrong.IVF increases the chance of multiple pregnancies -a possible danger to the mother's health&financial burden.
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In what two ways can foetal development be checked for genetic disorders?
The main screening method is amniocentesis but chromosomal analysis is also used.
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Talk about the method of amniocentesis.
Doctors use a long needle to remove some of the fluid that surrounds the baby. This contains skill cells from the baby, and the chromosomes in these can be analysed.
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What ethical issues does foetal screening raise?
If the foetus has a genetic defect, the parents may consider whether or not to continue the pregnancy, also foetal screening like amniocentesis can increase the risk of miscarriage.
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How can fertility be controlled in humans?
By sex hormones - contraceptive pill and fertility drugs.
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What is the definition of negative feedback mechanisms?
Mechanisms to lower raised levels of something, and to raise reduced levels of something.
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What do negative feedback mechanisms affect the production of?
Hormones in the menstrual cycle.
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What might high levels of one hormone inhibit?
The production of another hormone.
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Complete the sentence: When the _____________ of one hormone becomes ___ high, the release of another ______ will return it to a _____ level
When the concentration of one hormone becomes too high, the release of another hormone will return it to a lower level.
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Talk about negative feedback between the hormones: FSH and oestrogen
FSH stimulates the ovary to release oestrogen. Oestrogen inhibits the release of FSH. So when there's lots of FSH, oestrogen is released and FSH production is inhibited. This causes FSH level to fall.
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Talk about negative feedback between the hormones: LH and progesteron
LH indirectly stimulates the production of progesterone. Progesterone inhibits the release of LH. When there's lots of LH, progesterone is released. LH production is inhibited and the LH levels fall.
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What does oestrogen stimulate the release of?
LH
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Explain how contraception works.
Contains oestrogen or progesterone. These hormones prevent the production of FSH, which in turn stops eggs maturing in the ovaries. By preventing FSH release and ovulation, the pill mimics pregnancy.
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Other cards in this set

Card 2

Front

Describe the three main stages of the menstrual cycle.

Back

Menstruation – uterus lining breaks down (period), thickening of uterus lining and ovulation – egg released by ovary.

Card 3

Front

Is fertilisation and pregnancy guaranteed to all couples?

Back

Preview of the front of card 3

Card 4

Front

Give three causes of infertility.

Back

Preview of the front of card 4

Card 5

Front

In some - not all - cases of infertility, how can pregnancy be achieved?

Back

Preview of the front of card 5
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