1 of 40© Boardworks Ltd 2008 What is reproduction? Reproduction is one of the seven life processes. Humans use sexual reproduction to produce their young

1 of 40 © Boardworks Ltd 2008

What is reproduction?

Reproduction is one of the seven life processes.

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.

All living things reproduce.


The male reproductive system


The female reproductive system


Male or female?


Roles of the reproductive system


Sex cells – sperm

Sperm are produced in sex organs called testes.

In males, the sex cells are called sperm.

headtail middle piece

cell membrane nucleus containing DNA


Sex cells – egg

Eggs are produced in sex organs called ovaries.

In females, the sex cells are called eggs.

nucleus containing DNA

membrane jelly coat

cytoplasm


Sperm or egg?


What is fertilization?

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.

For a woman to become pregnant fertilization must occur.

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?


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.


Fertilization and implantation


Reproduction terms


What are contraceptives?

Contraceptives are devices designed to prevent pregnancy.

Sexually transmitted infections are diseases that can be passed on by sexual contact.

How do the different types of contraceptives work?

Contraceptives are not 100% reliable and some can cause other side effects.

Some types of contraception can also stop the spread of sexually transmitted infections.


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.


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.


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.


Which contraceptive?


Sexually transmitted infections


HIV and AIDS


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.

The umbilical cord joins 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.

umbilicalcord


How does the placenta work?


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.


What are the stages of development?


The stages of pregnancy


Birth

After 40 weeks of gestation, the baby is ready to be born. At this point, the head usually lies just above the cervix.

After a few minutes, the placenta comes away from the uterus wall. This is pushed out as the afterbirth.

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.

Birth begins with small contractions of the uterus wall, which gradually become stronger and more frequent.

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1 of 40© Boardworks Ltd 2008 What is reproduction? Reproduction is one of the seven life processes. Humans use sexual reproduction to produce their young