Higher Human Biology
Unit 2: The continuation of life
Chapter 16: Intervention
in Fertility!
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What you need to know: The
arrangements
Reproduction
Intervention in fertility
• Causes of infertility to include failure to ovulate, blockage of uterine
tubes, failure of implantation and low sperm counts.
• Treatment of infertility to include fertility drugs, in vitro fertilisation and
artificial insemination.
• The biological basis of contraception by calculation of fertile period and
by hormonal methods.
• Calculation of fertile periods from data on timing of menstruation, body
temperature and cervical mucus should be considered both from the
point of view of increasing the chances of pregnancy and as a possible
means of Contraception.
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Learning
Intentions
Understanding the
Continuation of Life
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Success
Criteria
• List the problems
associated with
infertility in both male
and female.
• Describe methods
used to treat infertility
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Infertility
• Medical condition of the reproductive system that
results in the inability to conceive or carry a pregnancy
to term
• Condition is diagnosed after a couple has had a year of
unprotected, regular intercourse without conceiving, or
when pregnancy occurs but does not result in a live
birth.
• 33% of infertility causes unknown
• Other factors that can contribute to infertility include
stress, smoking, alcohol use, excess weight and overall
health
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Infertility in Women
• Impaired ovulation due to
disease, birth defects, or
abnormal hormone production
• Blocked oviducts from infection
or scar tissue
• Inability of the uterus to hold
the embryo (this may be due to
a variety of reasons, including
scar tissue on the walls of the
uterus)
• Endometriosis
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Infertility in Men
• Low sperm count
• High percent of
abnormally-shaped sperm
• High percent of sperm that
are not moving forward
• Ejaculation dysfunction
• Sperm production can be
affected by blocked
passageways, fevers,
infections, or birth defects.
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Treatments summary
Current types include:
• In vitro fertilization (IVF):
Eggs and sperm are
collected and fertilised
in the laboratory before
the resulting embryo is
transferred to the womb.
• Fertility drugs
• Artificial insemination:
Sperm are inserted into
the womb at the time of
ovulation using a
catheter
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Treating Infertility In vitro fertilisation (outside the body in the lab)
• Stage 1
Hormonal
treatment to
stimulate
multiple
ovulation
• Stage 2
Several eggs
removed
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Treating Infertility In vitro fertilisation Con’t
- (outside the body in the lab)
• Stage 3
Eggs placed in a dish of nutrient
medium containing sperm to allow
fertilisation to occur OR injecting sperm
into egg.
• Stage 4
Fertilised eggs incubated in nutrient
medium to allow cell division to occur.
• Stage 5
Two or three embryos are chosen and
inserted into uterus via the vagina
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Watch this!
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Treating Infertility
In vitro fertilisation SUMMARY-
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Treating Infertility: Artificial
Insemination (Inside the body)
•
(
Insemination is the introduction of semen into the female reproductive
tract. It occurs naturally as a result of sexual intercourse.
Artificial insemination
- The insertion of semen by some other means other than sexual
intercourse.
• Used as a method of treating infertility
• If a man has a low sperm count or sperm, samples of his semen
can be collected and frozen until required.
• They are then defrosted and released into the female’s cervix
region during her most fertile period.
• Can also be used to insert semen of a donor who has a normal
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sperm count into a women
who’s
partnerinis sterile.
fertility
Worlds first
Pregnant man
http://www.dailymail.co.uk/news/article2019579/Worlds-pregnant-man-ThomasBeatie-unveils-muscular-body-3-babies.html
• Thomas Beatie, the transgender
man who gets pregnant by artificial
insemination.
• “Beatie, 34, now has has 3 healthy
children -which he has carried in the
womb he kept intact when he
became a man 10 years ago”
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Essay Questions:
SQA 2007
Give an account of
female infertility
(10)
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Learning
Intentions
Understanding
The Continuation
of Life
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Success
Criteria
Outline the biological
basis of contraception
by calculation of the
fertile period.
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Fertile Period – Day 1
Calculation of fertile period based on a 28
day cycle
• Day 1
– First day of menstrual flow – period starts
– Pre-ovulatory infertile phase
– FSH phase - stimulates development of egg and
production of Oestrogen. Oestrogen stimulates
repair of uterus.
– Cervix closed
– Endometrium 1 mm thick
– Temperature normal ~36.2°C
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Fertile Period – Day 14
• Day 14 (14 days after first day of
menstruation)
– Increase of oestrogen causes sudden flood of LH
– Increase of LH causes ovulation and development
of Corpus Luteum
– Cervix open – slippery, stretchy mucus present
– Endometrium 6mm thick
– Temperature normal ~36.2°C
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Fertile Period: Day 15-17
• Day 15 (15 days after first day of menstruation)
– Egg released into oviduct on this day
– Cervix open – slippery, stretchy mucus present (allow
sperm easy access to female reproductive system)
– Egg will only survive 24 hours after being released.
Therefore, will not be viable after day 16
– Sperm, however, can survive for 72 hours (3 days)
– Therefore, fertile days - 13th day, 14th day 15th day 16th
day only
– Endometrium 6 mm thick
– Temperature increase ~36.5°C
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Fertile Period: Day 18
• Day 18 (18 days after first day of menstruation)
– Egg has not been fertilised (infertile days)
– Dry days, Post-ovulatory days
– After ovulation mucus increases in viscosity
(thicker) due to increasing levels of
progesterone
– Endometrium 6 mm thick
– Temperature increase ~36.7°C.
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Fertile Period: Day 22
• Day 22 (22 days after first day of menstruation)
– Lack of LH leads to degeneration of Corpus
Luteum
– Oestrogen & progesterone levels drop
– Endometrium 5.5 mm thick
– Temperature increase ~36.8°C
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Fertile Period: Day 28
• Day 28 (28 days after first day of menstruation)
– Ovarian hormones very low
– Endometrium can no longer be maintained
– Menstruation ready to begin
– Endometrium 5.5 mm thick
– Temperature drops to normal ~36.2°C
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Fertile Period: Day 16 only if
egg fertilised
• Day 16 (16 days after first day of menstruation)
– If egg is fertilised, fertilised egg secretes hormone Human Chorionic Gonandotrophin (HCG)
– Has same effect as LH
– Presence of which is used in pregnancy testing
– Maintains Corpus Luteum which continues to secrete
progesterone and prevents menstruation
– After 6 weeks, placenta starts to secrete progesterone
– Cervical mucus becomes viscous due to high levels of
progesterone
– Pregnancy changes the mucus into a semi-solid plug
– This protects the fertilised egg from possible infection
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Menstrual cycle comparison of hormone
levels, follicle production and uterine changes
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Menstrual cycle: summary
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Menstrual cycle comparison of
hormone levels and uterine changes
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Menstrual cycle comparison of
hormone levels and body temperature
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Continuous versus cyclical fertility con’t:
Implications in calculating fertility!
Male – Continuously Fertile
• Negative feedback of testosterone maintains a relatively
constant level of gonadotrophic hormones (FSH & ICSH)
• Results in a fairly steady quantity of testosterone being
produced
Female - Cyclical Fertile
• Egg will only survive 24 hours after being released due to
hormone levels
• Sperm, however, can survive for 72 hours (3 days)
• Fertility is restricted to 3 – 4 days immediately following
ovulation
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Learning
Intentions
Understanding the
Continuation of Life
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Success
Criteria
• Know the biological
bases for
contraception.
• Describe hormonal
methods of
contraception as an
example of this.
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Methods of
Contraception
Contraceptive Pill
Male Condom
Female Condom
contraceptive patch
Contraceptive Implant
IUD
diaphragm contraceptive
emergency contraception
Biological Basis of Contraception
Contraception is the intentional
prevention of conception by natural
or artificial means.
Artificial Methods:
•Oral contraceptive pills
•Injections
•Implants
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Natural Methods:
•Temperature
•Mucus
•Rhythm methods
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Biological Basis of Contraception:
Natural Methods:Temperature.
Temperature
• One day after surge of LH temperature
increases by 0.5°C
• Remains elevated for duration of luteal
phase
• Fertility lasts 3 – 4 days
• By the 3rd day of the higher body temp the
egg has disintegrated.
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Biological Basis of Contraception:
Natural Methods: Mucus.
Mucus
• During fertile period mucus is thin &
watery to allow sperm easy access to
female reproductive system
• After ovulation mucus increases in
viscosity – becomes thicker, returning to
the infertile period.
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Biological Basis of Contraception:
Natural Methods: Rhythm method.
Rhythm Methods
• Methods of temperature and mucus
viscosity are used by couples who want to
have a child - they will know when the
best time to have sexual intercourse to
achieve successful fertilisation.
• If a couple do not wish to have children,
the rhythm method can also be used as a
contraceptive.
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Natural Contraception:
Summary
• Body temperature - body
temperature changes through
the menstrual cycle under the
influence of oestrogen and
progesterone. It rises slightly
after ovulation.
• Cervical mucus - the amount
of oestrogen and
progesterone alters the
quantity, texture and
appearance of cervical
mucus,
• Rhythm method - calculating
how long the menstrual cycle
lasts
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Biological Basis of Contraception:
Artificial Methods: Oral contraception.
Oral contraceptive pills
• Normally contain synthetic
progesterone sometimes combined
with synthetic oestrogen.
• Increases levels of progesterone &
oestrogen – exerts negative feedback
• Gonadotrophic hormones inhibited
• Little or no FSH secreted, follicle
maturation inhibited, ovulation fails to
occur
• Also thickens the mucus in the cervix
and makes the lining of the womb
thinner.
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Biological Basis of Contraception:
Artificial Methods: Injections + Implants
Injections & Implants
• Hormonal method of
contraception.
• Contraceptive implant slowly releases the
progesterone to
prevent ovulation.
Similar effects to pill
• Contraceptive
injections - contains
progesterone. Similar
effects to pill
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CONTRACEPTIVE
IMPLANT
44
When a woman wants to
become pregnant again!
• A woman must discontinue the pill.
• After lengthy use there may be a period of
delay before their bodies readjust and
return to a normal fertile state.
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Task: What to do now…..
• Complete card sort!
– Table 1.5: Biological methods of
contraception (from SCHOLAR).
– Once completes and correct coppy into your
notes or jotter.
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Task: Torrance-TYK pg119 Qu’s 1-3
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Task: Torrance AYK pg120-1
Qu’s 1-5
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Essay Questions:
SQA 2001 & 2010
Discuss the
biological basis of
contraception
(10)
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