GCSE Core Science
Human Biology
Key words
Stimulate, Inhibit,
Womb, Mature, FSH,
LH, Oestrogen,
Progesterone
GCSE Core Science
Human Biology
Objectives
By the end of the lesson I:
•
Can explain the role of FSH, LH, and oestrogen
in the menstrual cycle
•
Explain how each of the hormones affect each
other
•
Explain the role of FSH as a fertility drug
GCSE Core Science
Human Biology
Match up the key words with definitions
Ovulation
Menstrual cycle
2 of 3 Female Sex hormone
Release of egg cell from ovary
Oestrogen
Follicle
Male sex hormone
Progesterone
Fluid filled structure in which the ovum
matures in the ovary
Testosterone
28 day cycle controlled by hormones where lining
of uterus is released.
GCSE Core Science
Human Biology
Hormones are chemicals that act like messengers. They are
secreted by glands and carried in the blood from organ to
organ.
hormone
ovary
Cells in different parts of the
body recognize the hormones
and respond by making changes.
GCSE Core Science
Where are the major
glands of the body?
thyroid
adrenal
glands
testes
(males)
Human Biology
pituitary
gland
pancreas
ovaries
(females)
GCSE Core Science
Human Biology
Sex hormones
testes
(males)
ovaries
(females)
In males, the testes produce the sex hormone testosterone,
which makes male secondary sexual characteristics develop.
In females, the ovaries produce the sex hormones oestrogen
and progesterone.
These make female secondary sexual characteristics develop
and are involved in fertility and the menstrual cycle.
GCSE Core Science
Human Biology
The pituitary gland
The pituitary gland is a
pea-sized gland at the
base of the brain.
pituitary
It releases many
gland
YOU MUST KNOW
hormones and controls
•WHERE EACH OF THE FEMALE SEX HORMONES
several other glands in
ARE PRODUCED
the body.
•WHAT EFFECT THEY HAVE ON EGG PRODUCTION
The pituitary
gland AFFECTS THE PRODUCTION
•HOW EACH
HORMONE
OF THEproduces
OTHERStwo hormones
involved in fertility:
 follicle stimulating hormone (FSH)
 luteinizing hormone (LH).
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
IN SUMMARY
HORMONE
FSH
PRODUCED
EFFECT
Pituitary gland •Causes egg to mature
•Oestrogen to be produced
OESTROGEN
LH
PROGESTERONE
Ovaries
•Inhibits further production of FSH
•Stimulates production of LH
•Stimulate uterine lining to thicken
ready for implantation
Pituitary gland •Stimulates the mature egg to be
Ovaries
released
•Stimulates the uterus to thicken
ready for implantation
•Inhibits further production of LH
•When levels fall uterine lining
breaks down
GCSE Core Science
Inside the ovary
Human Biology
Day 15-28:
empty follicle turns
into corpus luteum
(yellow body)
immature
eggs
Day 1-13:
egg developing
inside the
growing follicle
Day 14:
ovulation – egg
released from follicle
GCSE Core Science
Human Biology
Uterus lining
uterus lining
thickness
The lining of the uterus becomes thicker with blood vessels and
more stable during the menstrual cycle. Why is this important?
period
2
4
6
8 10 12 14 16 18 20 22 24 26 28
days after start of period
A fertilized egg will bury itself (implant) in the uterus lining.
The egg needs a plentiful supply of oxygen and nutrients to
develop.
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
Questions
1) Using your graph of the menstrual cycle
i) Mark the letter A on the point where ovulation is most likely to
take place
ii) Mark the letter B where the female is most fertile
iii) Mark the letter C where menstruation is most likely to occur
GCSE Core Science
Human Biology
GCSE Core Science
Pregnancy
Human Biology
If the egg is fertilized, the uterus lining must not break down
otherwise the fertilized egg will not develop.
egg fertilized:
uterus lining
maintained, egg
implanted
corpus luteum (structure that develops
after the ovum is discharged but
degenerates if no pregnancy):
continues to produce
progesterone and oestrogen
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
The role of Hormones in the menstrual cycle
FSH released from pituitary
gland.
Produces follicle on ovary and
stimulates egg to mature.
Follicle secretes oestrogen.
High oestrogen levels makes
uterus lining thick and spongy
and stops the release of FSH
from pituitary
LH released from pituitary.
LH triggers ovulation
(release of egg cell)
If fertilisation occurs the
yellow body will secrete
progesterone, until placenta
is formed and then takes
over.
If no fertilisation occurs yellow
body disappears and progesterone
levels decrease.
This causes uterus lining to shed
and menstruation occurs.
Empty follicle (yellow body)
secretes progesterone.
Progesterone stops further
ovulation and prevents shedding of
uterus lining.
GCSE Core Science
Human Biology
Objectives
By the end of the lesson I:
•
Can explain the role of FSH, LH, and oestrogen
in the menstrual cycle
•
Explain how each of the hormones affect each
other
•
Explain the role of FSH as a fertility drug
GCSE Core Science
Human Biology
Key words
Contraception,
Fertility treatment
GCSE Core Science
Human Biology
Objectives
By the end of the lesson I:
•
Identify the issues involved in contraception and
fertility
•
Provide a two-sided argument for each of the
issues
•
Describe the role of hormones in oral
contraceptives.
GCSE Core Science
STARTER
Human Biology
•
Where is FSH produced?
•
What effect does the production of oestrogen
have on the production of FSH and LH?
•
What does LH do?
GCSE Core Science
Human Biology
Contraceptive pills contain progesterone and need to be taken
every day. How do they work?
no FSH received:
no egg maturing
Contraceptive pills mimic pregnancy, which means that the
ovaries do not produce any eggs.
GCSE Core Science
What is infertility?
Human Biology
Some couples are unable to conceive naturally. This is called
infertility. What might be some of the causes of infertility?
Women
Men
ovaries not releasing eggs
poor quality sperm
blocked fallopian tubes
(carry eggs from the ovaries
to the uterus)
blocked or damaged
tubes that carry sperm
problems with the uterus
lining
hormonal problems
low sperm count
hormonal problems
GCSE Core Science
Human Biology
How do fertility drugs work?
Fertility drugs are used to
help women who do not
produce an egg every month.
There are many different types
of fertility drug but they all work
by tricking the body into
producing more eggs.
Some fertility drugs contain
FSH. How do these work?
GCSE Core Science
What is IVF?
Human Biology
Sometimes, women have problems becoming pregnant
even after using fertility drugs. When this happens, they can
try in vitro fertilization, or IVF.
In vitro is Latin for ‘in
glass’ so IVF means
fertilization that takes
place outside of the
body and in laboratory
glassware.
Babies born by IVF are sometimes called ‘test-tube’ babies.
However, fertilization doesn’t take place in test-tubes but in a
special dish.
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
IVF and multiple births
Why does IVF increase the chances of multiple births?
GCSE Core Science
Human Biology
Multiple births are more
likely with IVF because
more than one embryo is
implanted into the uterus
to increase the chance of
a successful pregnancy.
Around 20% of IVF births are twins (compared with 1.25% of
normal births), and 0.5% are triplets. The number of triplets
was much higher 15-20 years ago because more embryos
were implanted at the same time.
Multiple births are the biggest risk of IVF for both the mother
and babies. They are more likely to result in premature births,
miscarriages, and long-term disability and ill health.
GCSE Core Science
The cost of IVF
Human Biology
IVF is expensive – around £3,000 for the treatment itself, plus
extra costs for consultation with doctors, drugs and tests.
Freezing embryos for further attempts at IVF also costs extra.
Couples may need to try
IVF several times (each
attempt is called a cycle)
before it is successful.
About 25% of IVF
treatments are funded by
the NHS. Women aged
between 23 and 39 years
can get one free IVF
cycle on the NHS.
GCSE Core Science
Human Biology
GCSE Core Science
Human Biology
Questions
2) Women that find it difficult to have children take FSH as part of
their fertility treatment.
i) Explain how FSH can help women to get pregnant.
ii) Explain why it is common for women that have this treatment to have
multiple births?
iii) The contraceptive pill is given to women to prevent pregnancy
GCSE Core Science
Human Biology
Objectives
By the end of the lesson I:
•
Identify the issues involved in contraception and
fertility
•
Provide a two-sided argument for each of the
issues
•
Describe the role of hormones in oral
contraceptives.