The document summarizes the key aspects of human reproduction. It describes puberty and the changes that occur during adolescence for both males and females. It then details the male and female reproductive systems and their functions. It explains the production of reproductive cells and the menstrual cycle. Finally, it outlines the processes of fertilization, pregnancy, and childbirth.

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SCIENCE 6. UNIT 3. HUMAN REPRODUCTION. C.E.I.P. SANTA ANA (Madridejos)
CONTENTS:
1.– Changes on the body. Puberty: Secondary sex characteristics.
2.– Male reproductive system.
3.– Female reproductive system.
4.– Reproductive cells. Male cells—Female cells. Menstrual cycle.
5.– Fertilisation and pregnancy.
6.– Childbirth.
USEFUL WORDS:
.– sexual reproduction
.– asexual reproduction
.– primary sexual
characteristics
.– secondary sexual
characteristics
.– adolescence
.– puberty
.– hormones
HUMAN REPRODUCTION is the process
in which human beings produce more human
beings similar to themselves.
Human reproduction is sexual. A male and a
female produce a new baby.
Reproduction is one of the vital function that living beings do.
All living beings can produce more beings similar to them-
selves, so human beings can also produce more human beings
similar to them.
In nature, there are two kinds of reproduction: asexual repro-
duction and sexual reproduction.
a.– Asexual reproduction: when only one individual produces
new living beings on its own (descendents). The new living
being inherits only the genes from that parent.
b.– Sexual reproduction: when a male and a female produce
new living beings. The new living being inherits genes from
both, its mother and its father.
On a baby, you can distinguish his/her primary sexual
characteristics: his/her reproductive organs.
1.– CHANGES ON THE BODY IN PUBERTY:
SECONDARY SEXUAL CHARACTERISTICS.
Before the moment a baby is born, reproductive
organs of boys and girls are different. These
differences from males and females are called
primary sexual characteristics.
Secondary sexual characteristics are features that
distinguish the two sexes, but that are not directly part
of the reproductive system.
Secondary sexual characteristics are changes in boys and girls during the adolescence or puberty.
Puberty is a period of time when a child’s body changes into an adult body (from 11 to 18 year for girls, and from
13 till 18 for boys ). There are physical and psychological changes, and its reproductive system reach maturity.
Sexual glands produce hormones. Males produce testosterone and females oestrogen that control these changes.
Breasts development
Facial hair
Pubic hair
Widen hipsPubic hair
Broad shoulders
Increase of hair on
body, arms and legs
Muscle
development
Mature genital
organs
FEMALE
Girls: .– Breasts development.
.– Hips widen.
.– The first menstrual cycle comes.
Boys: .- Adam’s apple is visible and voice gets lower.
.– Shoulders get broader and muscle development.
.– Hair on the face, body, arms and legs appears.
.- Testicles mature and produce sperm.
Boys and girls: .- Appearance of pubic and armpit hair for boys and girls.
armpit
1
Adam’s
apple
MALE

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C.E.I.P. SANTA ANA (Madridejos)
2.– MALE REPRODUCTIVE SYSTEM.
Male reproductive system produces male’s reproductive cells (sperm).
It produces millions of sperm a day.
1.- Testicles or testes are two small
round organs placed outside the ab-
dominal cavity. They are covered by
skin called scrotum.
They produce millions of sperm a day.
2.- Vas deferens are two tubes
from testicles to seminal vesicles.
Sperm travels through them.
3.- Seminal vesicles are two glands
next to the bladder. They produce sem-
inal fluid that mixes with the sperm.
Bladder
4.- Prostate gland is a gland under
the bladder. It produces prostate
fluid that mixes with the sperm.
5.- Urethra is a tube that con-
nects vas deferens and bladder
to the exterior.
Sperm or urine travel through
the urethra to the exterior.
6.- Penis is a cylindrical
organ that contains the
urethra.
Scrotum
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Bladder
3.– FEMALE REPRODUCTIVE SYSTEM. Female reproductive system has got two functions:
A.– It produces female’s reproductive cells (egg cell or ovum).
B.– It protects and feeds the new human being (embryo) till the birth.
1.- Ovaries are two organs (the size of an almond).
They produce and develop egg cells.
Ovaries release an egg a month through the Fallopian tubes.
2.– Fallopian tubes or oviducts are
two tubes that connect the ovaries to
the uterus.
3.– Uterus or womb is a cavity with
thick muscular walls. It contains the em-
bryo during the nine months of pregnancy.
Muscular walls
of uterus. Cervix is the lower
part of the uterus.
4.– Vagina is a muscular tube that connects
the uterus with the outside of the body.
5.– Vulva is the external
organ in the female repro-
ductive system, that protects
the entrance to the vagina.5
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3
4 .– testicles .– vas deferens .– seminal vesicles
.– prostate .-urethra .– penis
.– ovaries .– uterus .– fallopian tubes
.– vagina .– vulva5
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C.E.I.P. SANTA ANA (Madridejos)
4.– REPRODUCTIVE CELLS.
Human beings have sexual reproduction. Male individuals produce male sex cells (sperm) and female individuals
produce female sex cells (egg cell or ovum). Each sex cells have got genetic information, so new offspring will have
some characteristics from the father and others from the mother.
4.1.– SPERM (male sex cell).
Testicles produce millions of sperm a day, but they only can live
for a few hours.
They are very small and they are formed by three parts:
.– Head that contains the nucleus with the genetic infor-
mation.
.– Midpiece
.– Tail to move very fast looking for the egg cell.
4.2.– EGG CELL or OVUM (female sex cell).
Girls have all their female reproductive cells in follicles in their
ovaries from they were born. From puberty, one these eggs ma-
tures and is released every month.
It’s round and much bigger than sperm.
It has got a nucleus with the genetic information.
It hasn’t got active movement.
4.3.– MENSTRUAL CYCLE.
About every 28 days, one ovary releases an egg that is called ovulation. An egg lives only during 24 - 48 hours.
The uterus walls are thickening to prepare to develop the egg just in case the egg is fertilised.
If the egg is not fertilised, it will die and it will be expelled with the rest of the uterus lining (menstruation or
period). When menstruation begins, it is important to have a good hygiene.
Head
Midpiece
Tail
Sperm
Egg cell under
a microscope
1.- Menstruation:
The unfertilised egg and
the mucosal tissue with
blood vessels from uterus
are expelled.
(about 1st
- 6th
days)
2.- Preparation of the egg:
A follicle in an ovary ma-
tures an egg.
Uterus lining starts to grow
and thick again
4.-Preparation of the uterus:
The uterus lining continues to
thicken.
The egg moves into the uterus.
If the egg is unfertilized, the
uterus lining breaks down.
3.- Ovulation:
The follicle releases an egg. It
falls down through the Fallopi-
an tube to the uterus.
(Fertile time)
Egg released
Ovary
Follicle
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C.E.I.P. SANTA ANA (Madridejos)
5.A.– FERTILISATION.
When the man deposits millions of sperm in the woman’s vagina, many of them move up the vagina, into the uterus
and finally into the Fallopian tubes. If they find an egg, they will try to get inside, but only one sperm will enter. This
process is called fertilization, and the fertilised egg becomes a zygote (the first cell of the embryo)
1.– The egg is released
from the ovary and goes
down through the Fallopian
tube to the uterus.
2.– Sperm enter through the vagina,
and travels to the Fallopian tube.
3.– Lots of sperm get the egg, but only
one will enter and a zygote is formed
4.– The zygote divides
and forms an embryo.
5.– The embryo implants on the
uterus wall to grow and develop.
Fertilisation is the fusion of a sperm
with an ovum to produce a new organism.
Zygote is the first cell of the embryo.
5.B.– PREGNANCY.
Pregnancy lasts for about nine months (38 - 40 weeks) and finishes
in childbirth.
The embryo is developing, and brain, heart, arms and other organs are formed. After 8 weeks, it’s called foetus.
At the beginning, placenta, umbilical cord and amniotic sac are formed. After the 4th
month the fetus can hear, open
the eyes, move inside… During last three months, the fetus grows and the organs mature.
Pregnancy is the time the embryo/foetus
is developing inside the mother’s uterus.
Placenta is an organ
formed on the wall of the
uterus and supplies
nutrients, oxygen… from
the mother’s blood.
Umbilical cord links the
placenta to the fetus. It
contains arteries and veins
to transport blood with
oxygen, nutrients...
Amniotic sac is a bag with
liquid inside (amniotic
fluid) to protect the fetus.
It’s formed at the same time
as the placenta
USEFUL WORDS:
.– fertilisation
.– egg .– sperm
.– zygote .– embryo
.- fetus / foetus
.– placenta
.– umbilical cord
.– amniotic sac
.– amniotic fluid
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C.E.I.P. SANTA ANA (Madridejos)
6.– CHILDBIRTH.
About 9th
month of pregnancy, the fetus is totally mature and
ready to be born. It’s about 50cm high and weights about 3,3
kg. It’s time for labor or childbirth.
Normally, baby’s head goes out first. But sometimes, the fetus
is upside-down and he/she can’t go out, so the doctor has to
make a surgical operation called caesarean birth.
USEFUL WORDS:
.– labor or childbirth .- caesarean birth
.– dilation .– expulsion .– placenta delivery
Labor has got three stages:
.– Dilation
.– Expulsion
.– Placenta delivery
1.- Dilation: 6 - 12 hours (or more in first
child). It begins with regular uterine contracti-
ons and ends with full dilation of the cervix
(about 10cm)
2.– Expulsion: the fetus is pushed out through
the vagina by the contractions of the uterus.
When the fetus comes out the doctor cuts the
umbilical cord (its scar is the navel).
After a few seconds, the baby starts to cry and
breath.
3.– Placenta delivery: is the last stage of the
labor. Contractions of the uterus expel the pla-
centa and the rest of tissues.
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