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Human Reproduction

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What is reproduction?
Reproduction is one of the
seven life processes.
All living things reproduce.
Humans use sexual
reproduction to
produce their young.
In order to do this, the two
parents (male and female)
have different reproductive
systems and organs that
produce different sex cells.
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The male reproductive system
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The female reproductive system
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Male or female?
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Roles of the reproductive system
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Sex cells – sperm
In males, the sex cells are called sperm.
tail
middle piece
cell membrane
head
nucleus containing
DNA
Sperm are produced in sex organs called testes.
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Sex cells – egg
In females, the sex cells are called eggs.
nucleus containing
DNA
cytoplasm
membrane
jelly coat
Eggs are produced in sex organs called ovaries.
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Sperm or egg?
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What is fertilization?
For a woman to become pregnant fertilization must occur.
Fertilization is the fusing of an egg and a sperm cell. In this
process the sperm’s nucleus will join with the egg’s nucleus.
Females produce an egg
approximately every 28 days.
This is called ovulation.
Males continually produce
sperm in the testes.
How do these cells come into close contact with each other?
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Sexual intercourse
During sexual intercourse
the man inserts his penis
into the woman’s vagina.
Millions of sperm cells are
ejaculated into the top of
the vagina.
They enter the uterus through
the cervix, where the sperm
cells may meet an egg.
Now fertilization can occur.
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Fertilization and implantation
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Reproduction terms
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What are contraceptives?
Contraceptives are devices designed to prevent pregnancy.
Some types of contraception can also
stop the spread of sexually
transmitted infections.
Sexually transmitted infections are
diseases that can be passed on by
sexual contact.
Contraceptives are not 100% reliable
and some can cause other side effects.
How do the different types of contraceptives work?
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Different types of contraceptives

Condoms – a latex barrier worn
over an erect penis. This barrier
prevents sperm entering the
vagina and causing pregnancy.
It can also help to stop the spread
of sexually transmitted infections.

Contraceptive pill – a pill containing a mixture of
hormones taken every day. These hormones stop the
release of eggs, preventing pregnancy. However the pill
cannot protect against disease.

Diaphragm and cap – these are barriers inserted into
the vagina to prevent sperm reaching the egg.
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Alternatives to contraception
Some people in long term relationships choose to use
natural family planning instead of contraceptives.
This involves working out
when the woman is fertile
and avoiding sexual
intercourse at these times.
This method does not
have any effect on the
body, but it can be an
unreliable form of birth
control and does not
protect against sexually
transmitted infections.
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Emergency contraception
Emergency contraception is available to women that
have had unprotected sex, to prevent pregnancy.
This is in the form of a
pill, often called the
‘morning after pill’. It
should be taken within 3
days of unprotected sex,
in order to be effective.
However, it does not protect against sexually
transmitted diseases and it can have side effects.
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Which contraceptive?
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Sexually transmitted infections
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HIV and AIDS
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The placenta
How does an embryo receive food and oxygen and how
does it get rid of waste?
An embryo forms a structure called the placenta, which
attaches to the uterus wall.
umbilical
The umbilical cord joins
cord
the fetus to the placenta.
In the placenta, food and oxygen
diffuse from the mother’s blood
into the blood of the fetus.
Carbon dioxide and waste
products diffuse from the blood of
the fetus into the mother’s blood.
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How does the placenta work?
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From embryo to fetus
In the earliest stages of development, a human baby is
called an embryo.
After the first eight weeks of pregnancy, a human embryo
is then called a fetus.
At this stage, the fetus has all the main human features.
The fetus continues to
develop and grow inside
its mother’s uterus for a
total of 40 weeks.
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What are the stages of development?
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The stages of pregnancy
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Birth
After 40 weeks of gestation, the baby
is ready to be born. At this point, the
head usually lies just above the cervix.
Birth begins with small contractions
of the uterus wall, which gradually
become stronger and more frequent.
Eventually the contractions cause the amnion to break
and the fluid escapes. The cervix then widens and dilates
as the baby is pushed through the vagina.
After a few minutes, the placenta comes away from the
uterus wall. This is pushed out as the afterbirth.
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What happens during puberty?
Humans are born with a complete set
of sex organs. However, they do not
usually become active until between
the ages of 10 and 18.
In males, the testes start to make
sperm, and in females, the ovaries
start to release eggs.
This stage of development is called
puberty, and is caused by hormones.
During this important time, many
changes take place in the bodies
of young men and women.
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Puberty in males
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Puberty in females
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Menstruation
An important part of puberty for girls is the beginning of
their monthly cycle. This is known as the menstrual cycle.
The menstrual cycle
involves the preparation of
the uterus lining so that it
can receive a fertilized egg.
If an egg is fertilized, it can
implant itself in the prepared
uterus lining.
If the egg is not fertilized, the lining of the uterus
breaks down and is lost from the body. This is called
menstruation, or a period.
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Periods
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Glossary
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Anagrams
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Multiple-choice quiz
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