Biological Control of Fertility Flashcards

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1
Q

Give 4 examples of factors which can affect a person’s fertility?

A

weight
stress
disease
pollutants e.g. cigarette smoke

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2
Q

What are the 2 types of fertility?

A

Continuous

Cyclical

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3
Q

What do men have the potential to father?

A

a child from puberty onwards due to the negative feedback effect of testosterone

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4
Q

What does the negative feedback effect of testosterone maintain?

A

a constant level of the pituitary hormones FSH and ICSH in the bloodstream, resulting in the steady release of testosterone

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5
Q

What does the steady release of testosterone cause?

A

sperm to be continually produced in the testes , resulting in men being fertile throughout their lives.

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6
Q

When do women only release eggs?

A

from puberty until they reach the menopause

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7
Q

What is the menopause?

A

when ova are no longer released from the ovaries and menstruation no longer occurs.

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8
Q

In most women when does menopause occur?

A

45-55

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9
Q

When can a woman fall pregnant?

A

Each month there is only a limited number of days either side of ovulation

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10
Q

What does the interaction of the pituitary and ovarian hormones result in?

A

the period of fertility in females only lasting for 1-2/3-4 days

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11
Q

What is a woman’s fertility?

A

cyclical

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12
Q

What are the 2 main indicators that can be used to calculate a woman’s fertile period?

A

body temperature

consistency of cervical mucus

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13
Q

Why are the 2 indicators useful?

A

as they can be used to predict when a woman will ovulate and therefore when she is most likely to fall pregnant.

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14
Q

What is the method of fertility by using the indicators to predict when a woman will ovulate and therefore when she is most likely to fall pregnant called?

A

rhythm method

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15
Q

What are the processes of menstruation and ovulation are separated by?

A

intervals of about 2 weeks

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16
Q

Roughly 1 day after the surge in LH in the bloodstream that triggers ovulation, what happens to a woman’s body temperature?

A

rises by about 0.2-0.5’c

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17
Q

What happens after the body temperature rises?

A

it remains at this level for the duration of the luteal phase of the menstrual cycle

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18
Q

How long does the period of fertility last for?

A

about 1-2 days (after ovulation)

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19
Q

After a third daily recording of this increased body temperature what happens to the period of infertility?

A

the period of fertility is resumed as the unfertilised egg will have disintegrated

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20
Q

What happens to the cervical mucus during the fertile period?

A

the cervical mucus is secreted into the vagina

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21
Q

Describe the consistency of cervical mucus during the fertile period?

A

thinner, slippery and stretchy to allow sperm easy access to the female reproductive system

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22
Q

Why does the consistency of cervical mucus change during the fertile period?

A

due to the increasing oestrogen levels in the follicular phase

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23
Q

What happens to the consistency of cervical mucus after ovulation?

A

the mucus gradually increases in viscosity under the action of progesterone, showing that the system has returned to the infertile phase

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24
Q

What has the advancement of modern medicine allowed?

A

the development of a number of methods which can be used to overcome infertility

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25
Q

Give 4 examples of treatments used to help overcome infertility

A

stimulating ovulation
artificial insemination
IVF
ICSI

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26
Q

Why might a woman fail to ovulate?

A

failure of pituitary gland to secrete enough FSH or LH

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27
Q

If a woman fails to ovulate due to the failure of pituitary gland to secrete enough FSH or LH. How can ovulation be successfully stimulated?

A

by drugs that prevent the negative feedback effect of oestrogen on FSH secretion.
drugs that mimic the normal action of FSH and LH

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28
Q

What can ovulation stimulating drugs cause?

A

‘super-ovulation’ that can result in multiple births or be used to collect ova for IVF programmes

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29
Q

What is artificial insemination?

A

the insertion of semen into the female reproductive tract by some other means than sexual intercourse

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30
Q

Why might artificial insemination be used?

A

if a man has a low sperm count - several samples of his semen can be collected over a period of time and each preserved by freezing . They are defrosted and released into the female’s cerivical region at a time when she is most likely to be fertile.

if Donor semen is required - if the male is sterile, healthy semen samples may be obtained from a donor

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31
Q

What is the problem of infertility caused by which results in the use of IVF?

A

A blockage of the oviducts

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32
Q

What does IVF enable?

A

fertilisation to occur outside the bodies of the would-be parents in a culture dish

33
Q

What can IVF be used in conjunction with and what does this help do?

A

Pre-implantation Genetic Diagnosis (PGD) to identify single gene disorders an chromosomal abnormalities

34
Q

What is stage 1 of IVF?

A

The woman is given hormonal treatment to stimulate multiple ovulation (several eggs released)

35
Q

What is stage 2 of IVF?

A

A surgical procedure is employed to remove several of these eggs from around her ovary using a piece of equipment similar to a syringe

36
Q

What is stage 3 of IVF?

A

The eggs are mixed with sperm in a culture dish of nutrient medium to allow fertilisation to occur. Alternatively a sperm may be injected directly into an egg at this stage (ICSI)

37
Q

What is within the nutrient medium?

A

glucose

amino acids

38
Q

What is stage 4 of IVF?

A

The fertilised eggs are incubated in the nutrient medium for 2-3 days to allow cell division to occur and form embryos each composed 8 or more cells

39
Q

What is stage 5 of IVF?

A

2/3 of the embryos are chosen and then inserted into the vagina into the mother’s uterus (now ready for implantation)

40
Q

What is stage 6 of IVF?

A

The raining embryos are frozen and stored in case a second attempt at implantation is required

41
Q

Why might pre-implantation genetic diagnosis be useful for couples?

A

couples at risk of having a child with a serious genetic condition

42
Q

What PGD be used in conjunction with?

A

IVF to identify single gene disorders and chromosomal abnormalities

43
Q

In terms of PGD, what happens during IVF before the embryo is inserted into the female’s uterus?

A

a sample of cells is collected from the embryo to test for known chromosomal or gene defects

44
Q

Why do some people support the use of PGD?

A

it can offer reassurance to couples who would otherwise be at high risk of producing children with serious genetic disorders.

45
Q

Why do some people think PGD is morally wrong?

A

it is morally to interfere with the process of conception by making it selective

46
Q

What do about 6% of female patients undergoing IVF found to suffer?

A

hyper stimulation of the ovaries

47
Q

What can the drugs used during IVF cause?

A

too many eggs to be produced resulting in the ovaries becoming swollen and sore

48
Q

What are medical experts concerned that IVF may be exposing many women to?

A

an increased risk of ovarian cancer in later life

49
Q

What do most children conceived through IVF tend to have?

A

lower body mass at birth compared to that of full-term babies

50
Q

What are children who are born with a low body mass more likely to suffer from?

A

long-term health problems such as obesity, diabetes, heart conditions an hypertension in later life

51
Q

What is intra-cytoplasmic sperm injections (ICSI)?

A

when only one sperm is injected directly into an egg cell

52
Q

What happens to the sperm before it is injected into the egg during ICSI?

A

It is immobilised by removing its tail

53
Q

Describe ICSI?

A

The head of sperm is drawn into a needle and injected directly into the egg to achieve fertilisation.

54
Q

When is ICSI commonly used?

A

if mature sperm are defective or very low in number

55
Q

What is contraception?

A

the intentional prevention of conception or pregnancy by natural or artificial means

56
Q

What does the rhythm method depend on ?

A

the women developing a sound knowledge of her own menstrual cycle. She can, with practice, be confident in her ability to identify her fertile and decide to abstain from sexual intercourse at this time. This information can also be useful if a couple is having difficulty in conceiving as they would then intercourse at this time to increase their chances

57
Q

Name a natural method of contraception?

A

rhythm method

58
Q

What are the 2 categories of artificial contraception?

A

Physical (barrier)

chemical

59
Q

What does a barrier method do?

A

physically blocks the ability of sperm to reach an ovum

60
Q

Give 3 examples of barrier methods of contraception?

A

condoms
diaphragm
sterilisation

61
Q

What is sterilisation?

A

a medical technique which permanently prevents a person from being able to reproduce

62
Q

What is sterilisation in men called?

A

a vasectomy

63
Q

What is sterilisation in women called?

A

tubal ligation

64
Q

How effective is sterilisation?

A

it is a highly effective means of contraception but it is normally irreversible

65
Q

What does a vasectomy involve?

A

the cutting and tying of the two sperm ducts preventing sperm being released from the testes

66
Q

What does tubal ligation involve?

A

the cutting and tying of the two oviducts to prevent eggs meeting sperm and reaching the uterus

67
Q

What are chemical contraceptives based on?

A

combinations of synthetic hormones that mimic negative feedback preventing the release of FSH/LH

68
Q

Who are chemical contraceptives only available for?

A

Females

69
Q

How are chemical contraceptives usually taken?

A

orally as a daily pill

70
Q

What do all formulations of hormones contain?

A

synthetic forms of oestrogen and/or progesterone

71
Q

What are the 2 main types of contraceptive pill?

A

progesterone only pill

morning after pill

72
Q

What progesterone only pills also called?

A

mini pill

73
Q

What do mini-pills contain?

A

only very high concentrations of synthetic progesterone

74
Q

How do mini-pills work?

A

by causing the thickening of cervical mucus, which reduces the viability of sperm and their access to the egg

75
Q

What is the morning after pill also known as?

A

emergency hormonal contraception pills

76
Q

What does the morning after pill often contain?

A

higher doses of the hormones (progesterone and oestrogen) found in standard oral contraceptive pills.

77
Q

When are the morning after pills taken?

A

after unprotected sexual intercourse to prevent implantation from occurring if fertilisation has taken place unintentionally

78
Q

Ideally when should the morning after pills be taken?

A

as soon after unprotected sex as possible but may be effective up to 72 hours