1. Human Reproduction
IGCSE Biology

2. Human Reproduction
Objectives:
To be able to recall the parts of the male and female reproductive
systems.
To be able to recall the functions of the parts of the male and female
reproductive system.
To be able to describe the journey of the egg and sperm through the
reproductive system.
Thursday, 30 May 2013
Key words:
sexual reproduction, sex cells, sperm, penis,
ovary, oviduct, uterus, vagina, penis, sperm
tube, testis, scrotum, cervix, glands, urethra,

4. True or false?
You can’t get pregnant the first time you have
sex.

5. True or false?
You can’t get pregnant the first time you have
sex.
FALSE

6. True or false?
Sperm can live for up to 3 days inside a
woman’s body.

7. True or false?
Sperm can live for up to 3 days inside a
woman’s body.
TRUE

8. True or false?
You can’t get pregnant if you have sex
standing up

9. True or false?
You can’t get pregnant if you have sex
standing up
FALSE

10. True or false?
Boys start to have wet dreams when they reach
puberty

11. True or false?
Boys start to have wet dreams when they reach
puberty
TRUE

12. True or false?
Condoms help to prevent the spread of
sexually transmitted diseases.

13. True or false?
Condoms help to prevent the spread of
sexually transmitted diseases.
TRUE

14. True or false?
Girls should not swim or play sport during
their period.

15. True or false?
Girls should not swim or play sport during
their period.
FALSE

16. True or false?
A baby girl has eggs already inside her.

17. True or false?
A baby girl has eggs already inside her.
TRUE

18. True or false?
Taking the pill means you can’t get pregnant.

19. True or false?
Taking the pill means you can’t get pregnant.
FALSE

20. True or false?
You can’t get pregnant during a period.

21. True or false?
You can’t get pregnant during a period.
FALSE

22. True or false?
The pill stops you from getting diseases

23. True or false?
The pill stops you from getting diseases
FALSE

24. Find a partner
• we instinctively select mates who will enhance
the survival of the species.
• Men are drawn to classically beautiful women
-clear skin
-bright eyes
-shiny hair
-good bone structure
-nice lips
-rosy cheeks

25. But why…????
• NOT because of fad or fashion
• these qualities indicate youth and
robust health
• signs that a woman is in the peak of her
childbearing years.

26. And what about the girls?
• youth and physical health aren't essential to
the male reproductive role
• women instinctively favour mates with
pronounced "alpha" qualities,
-ability to dominate other males
-bring home more than their share of the kill.
• The assumption is that male dominance
ensures the survival of the family group more
than youth or beauty.

27. What is reproduction?
Sexual reproduction
involves two parents who
have sex organs which
produce sex cells.
Reproduction is the production of new members of a species,
replacing those who die due to old age, disease, competition etc.
It is divided into two main types:

28. Sex cells
Sex cells are called gametes
Most animals reproduce sexually so they need:
The male gametes are sperm
The female gametes are eggs
(or ova)
The sperm and egg have to meet and a sperm nucleus must fuse (join)
with the egg nucleus.
This process is called fertilisation.
A fertilised egg is known as a zygote

30. Each gamete contains half the number of parental chromosomes. The two gametes
fuse together during fertilisation to make a new individual with a full set of
chromosomes

31. Male gamete = sperm – produced in testes and deposited though intercourse (mating) into female reproductive tract by
male reproductive system
Female gamete – egg (ovum) – produced in ovaries – fuses with male sperm to form a zygote (which develops into a
baby) in the female reproductive tract
23
23

32. Structure of SPERM

34. Sperm - parts & Functions
• Nucleus – contains chromosomes
• Head – Contains the nucleus & lysosmes (
acrosome)
• Mid piece ( neck )- contains lot of
mitochondria , which makes ATP for the
sperms to swim

35. • Tail ( flagellum ) - made from proteins &
microtubules , which ATP to propel the sperm
forwards
• Acrosome – A specially modified lysosome in the
sperm’s head . The acrosome swells and bursts
when the sperm comes in contact with the follicle
cells and zona pellucida. The enzymes in the
acrosome digest the follicle cells and zona
pellucida to allow the cell membranes of the
sperm and ovum to fuse .
Sperm - parts & Functions

36. • Cytoplasm – Very little , which means cells are
small and therefore can be released in large
numbers .It also assists motility ( movement of
sperms )
Sperm - parts & Functions

37. Human Reproductive
System

38. Stages in Sexual Reproduction in Humans
1.Once a month an egg cell is released from the ovary. This is called ovulation.
2.The egg cell moves into the oviduct.
3.Many sperm are deposited in the vagina during sexual intercourse. They pass
through the cervix, into the uterus and along the oviduct.
4.A single sperm meets the egg cell in the oviduct and fertilisation (conception)
takes place here.
5.The head of the sperm, which contains the nucleus (23 chromosomes) enters
the ovum and fuses with the nucleus of the ovum, which also contains 23
chromosomes. Fusion of the sperm and egg nucleus results in a single cell
termed the zygote (46 chromosomes)
6.The zygote divides by mitosis to form the embryo. The embryo embeds itself
in the uterus wall and divides further. A placenta (exchange surface) is formed
between the developing embryo and the maternal blood vessels in the uterus
wall. The cells continue to divide and become specialised into tissues, which
then form organs. At this stage the individual is termed the foetus. The foetus
than develops into the baby.
7.The baby is delivered into the outside world at birth after 9 months (gestation
period), by the process of parturition (or labour)
The offspring varies genetically and phenotypically (physically) from the parent

39. Male Reproduction
Ejaculation
• Passage of sperm and semen
from the penis.
Epididymis
• Cord-like structure in the back
of testes
Penis
• The organ for reproduction and
urination.
Prostate gland
• Secretes an alkaline fluid that
neutralises the acidy.
Scrotum
• Sacs that regulates temperature
for sperm production.
Semen
• A combination of sperm and
fluid.
Sperm
• Male sex cell produced by
testicles.
Testicles
• Organs in the scrotum that
produces sperm and
testosterone.

40. Male
Name Function
sperm tube
sperm travel along
it
urethra
sperm & urine
released through it
testes produces sperm
penis
for placing sperm
into female
Human Reproductive System

41. Female Reproduction
Cervix
• Neck or opening to the uterus.
• Strongest muscle in the body.
Fallopian tubes
• Two tubes which connect the
ovaries to the uterus and carry the
egg to the uterus.
Ovaries
• Egg shaped
• Produces female hormones
• Stores and releases ovum.
Ovulation
• When an egg is released from the
ovary and moves down the
fallopian tube.
Uterus
• A hollow, muscular organ that
protects and nourishes the foetus.
Vagina
• Empty passageway leading from the
vaginal opening to the uterus.
Vulva
• The general term for all the
external female sex organs.

42. Human Reproductive System
Female
Name Function
oviduct
(egg tube)
eggs released
into it, site of
fertilisation
ovary produces eggs
uterus
where fertilised
egg implants
vagina
sperm deposited
here

43. Outline the route taken from
the testes by the sperm as it
leaves the body
Sperm leaves the testes and
travels down the sperm duct...
... which travels past/through
the glands.
The glands provide the
sperm cells with food so that
they have energy for
swimming
The sperm duct joins the
urethra...
... which carries the sperm
out of the body.

44. Fallopian Cillia

45. Comparison of sperm & Ovum
Sperm Ovum
1.Size Smaller than ovum and is
motile
Large cell, incapable of
independent movement
2. Stucture Long tail for movement ,
powered by mitochondria
Wafted oviducts by cilia and
muscular contractions
3. Food
reserves
Littlle or no , gets energy
from nutrients in the
seminal fluid
Cytoplasm contains protein
and lipid food reserves
4. Special
feature
Head contains acrosome to
hydrolyse the zona pellucida
Head surrounded by a jelly
like coat – the zona pellucida
which hardens after one
sperm penetrates

46. Sperm Ovum
5. Production Sperms are produced in large
numbers The sperm production
is continuous.
The sperm production and
maturity takes about 70 -72 days.
which is longer compared with
ovum production
Only one ovum is
produced
Normal male produces over 100
million sperm per ejaculation;
fewer than 100 reach vicinity of
egg; one penetrates.
There are two ovaries in
female. So one side
ovary will ovulate
alternative cycles.
.
Comparison of sperm & Ovum

48. Sperm and Egg
Thursday, 30 May 2013
http://www.bbc.co.uk/learningzone/clips/an-introduction-to-fertilisation/116.html
http://www.youtube.com/watch?v=vXNaTRs83hE&feature=related

49. External fertilisation
In some animals fertilisation takes place
outside the body.

50. Internal and external fertilisation
1. Discuss with the person next to the following:
Why do fish need to produce so many babies? Why are humans pregnant for longer than
cats? Which animal is the best mother?
Thursday, 30 May 2013
Animal Number of egg cells produced Type of fertilisation
Bat 1
Frog 20 000
Cat 4
Fish 5 000 000
Tiger 2

51. Thursday,30May2013
Rearrange the table

52. Answers
Ovary Where the eggs are made.
Oviduct Where eggs are carried to the uterus.
Uterus Where a baby grows during pregnancy.
Cervix Entrance to the uterus.
Vagina Where the penis goes during sex.
Urethra The tube that takes urine and semen out of
the body.
Penis Used to put semen into the female.
Sperm
tube
The tube that caries sperm from the testis.
Testis Where sperm are made.
Thursday,30May2013

53. Puberty

54. The process of physical
changes by which a child's
body becomes an adult
body capable of
reproduction.
Puberty is initiated by
hormone signals.

55. All the machinery necessary for going through puberty is
present at birth, but the body keeps it switched off for
many years. Eventually, the mechanism that prevents
puberty winds down, and hormones that previously have
been held in check can begin to exert their influence on
the body. A part of the brain called the hypothalamus
starts to release pulses of hormone, every 90 minutes or
so. This stimulates the pituitary gland (also in the brain)
to produce luteinising hormone (LH) and follicle-
stimulating hormone (FSH), which in turn cause a girl's
ovaries to start producing other hormones.

56. Definition of a hormone
A chemical substance produced in the
body that controls and regulates the
activity of certain cells or organs.

57. Hormone Where
Produced?
What it does? Gender Picture
FSH Pituitary Gland
in Brain
Stimulates eggs
and menstrual
cycle
F 1
Progesterone Ovary Prepares the
lining of the
womb
F 2
Oestrogen Ovary
Prepares lining
of the womb.
Secondary
sexual
characteristics
F 2
Testosterone Testes
Ovary
Male sexual
characteristics M
F
3
Pituitary
Hormone
Pituitary Gland
in Brain
Master Gland for
puberty
initiation
M F 1

58. During puberty, oestrogen stimulates breast
development and causes the vagina, uterus
(womb) and Fallopian tubes (that carry eggs to the
womb) to mature. It also plays a role in the growth
spurt and alters the distribution of fat on a girl's
body, typically resulting in more being deposited
around the hips, buttocks and thighs. Testosterone
helps to promote muscle and bone growth.

59. A boy's voice gets deeper, his muscles develop and his chest gets
broader. Hair starts to grow on his face, legs, chest, and under his
arms. In due course he will need to start shaving.
During this time his penis and testicles will also grow bigger and
longer. Hair, called pubic hair, will also start to grow at the base of his
penis. As a boy gets older, this hair will grow thicker and courser.

60. What does it mean for a boy's voice to break?
This is just a way of saying that a boy's voice will get
deeper.
Sometimes it can happen very quickly, perhaps even
overnight. But often boys go through a period where
they have trouble controlling their voice, and it goes up
and down in pitch as they talk. This can be embarrassing,
but it usually doesn't last very long and all boys' voices
will eventually settle down and sound deeper.

62. Puberty/adolescence
Between the ages of 10 and 15 changes will
start to happen to your bodies

63. Puberty/adolescence
Puberty is controlled by sex hormones
produced by the ovaries and testes

64. Puberty/adolescence
Girls normally start puberty before boys

65. Girls and boys
Underarm and pubic hair will start to grow

66. Girls and boys
Stronger body smell

67. Girls and boys
Acne (spots)

68. Girls and boys
Growth spurts

69. Girls and boys
Emotional changes!

70. Girls only
Breasts develop

71. Girls only
Ovaries start to release eggs (periods start)

72. Girls only
Hips get wider

73. Boys only
Voice deepens (“breaks”) and shoulders
widen

74. Boys only
Hair start to grow on face and chest

75. Boys only
Testes and penis get bigger

76. Boys only
Testes start to produce sperm (“wet dreams”
may start)

77. When a girl goes through puberty one of the changes that
occurs is that she will begin to have periods.
This is the female body’s way of preparing to reproduce
A woman’s reproductive system works on a 28 day cycle
This cycle is known as the
menstrual cycle
The menstrual cycle consists of
A number of stages
In this part of the lesson we will learn what
those stages are.....

78. Hormones
• Four hormones involved in controlling
menstruation
Name Made… Function
FSH Pituitary Stimulates one egg cell
to develop (become
follicle)
Oestrogen Follicle (ovary) Stimulates rebuilding
of the uterus wall
LH Pituitary Stimulates follicle to
burst and release the
ovum
Progesterone Corpus Luteum (ovary) Completes
development of uterus
wall, promotes
glycogen storage

79. Day 1 – 7
The menstruation cycle
starts with the first day
of a woman’s period.
This is the name given to
the time of the month
when the lining of the
uterus comes away and
exits through the vagina
as blood.

80. Day 7 - 13
Around day 7 the blood flow
stops.
The lining of the uterus
begins to build up again.
At this time an egg starts to
mature in one of the ovaries

81. Day 14 (The Middle)
On the 14th day which is the
middle of the cycle, an egg is
released by an ovary into the
oviduct.

82. Day 14 - 17
The egg can last up to 3 days
after it is released from the
ovary.
During this time the egg
travels down the oviduct and
into the uterus hoping to be
fertilised.

83. Day 18 - 28
If the egg is not fertilised
then the lining of the uterus
begins to break down.

84. Day 1 – 7
The cycle starts over
again expelling the lining
of the uterus and the
egg.
Remember this is known
as a period or
menstruation.
The cycle starts over again...

85. Foetal Development and
Giving Birth

86. Fertilization
Fertilization, the joining of the sperm and the egg in the fallopian tube (below) to form a
unique human being, occurs.

87. Only 30 hours later
This is a fertilized egg
only thirty hours after
conception.
Magnified here, it is no
larger than the head of a
pin.
Still rapidly dividing, the
developing embryo, called
a zygote at this stage,
floats down from the
fallopian tube and
towards the uterus.

88. Weeks 3-5
The embryo’s tiny heart
begins to beat by day
twenty-one.
Arm and leg buds are visible
and the formation of the
eyes, lips, and nose has
begun.
The spinal cord grows
faster than the rest of the
body giving a tail like
appearance which
disappears as the embryo
continues to grow.
The placenta begins to
provide nourishment for the
embryo.

89. Week 7
Major organs have
all begun to form.
The embryo has
developed its own
blood type,
unique from the
mother’s.
Hair follicles and
knees and elbows
are visible.
Facial features are
also observable.
The eyes have a
retina and lens.
The major muscle
system is
developed and the
embryo is able to
move.

90. Weeks 8-12
The embryo is reactive to its
environment inside the amniotic sac
where it swims and moves.
Hands and feet can be seen.
At the end of week 8, the embryonic
period is over and the foetal stage
begins.

91. Weeks
13-16
The brain is fully
developed and the foetus
can suck, swallow, and
make irregular breathing
sounds.
Foetus can feel pain.
Foetal skin is almost
transparent.
Muscles tissue is
lengthening and bones
are becoming harder.
Liver and organs produce
appropriate fluids.
Eyebrows and eyelashes
appear and the foetus
makes active movements
including kicks and even
somersaults.

92. Weeks
20-24
A protective waxy substance
called vernix covers the skin.
By birth, most of the vernix will
be gone but any that is left is
quickly absorbed.
Foetus has a hand
and footprints and fingerprints
are forming.
Foetus practices breathing by
inhaling amniotic fluid into its
developing lungs.

93. Weeks 25-28
Rapid brain development occurs
during this period and the nervous
system is able to control some bodily
functions.
The foetus’ eyelids now open and
close. At 25 weeks there is a 60%
chance of survival if born.
There is a rapid increase in the
amount of body fat the foetus
has.
Rhythmic breathing occurs,
but the lungs are not yet
mature.
The foetus sleeps 90-95% of
the day. (ERIN)
At this point there the survival
rate is above 95% if the baby is
born
Weeks 29-32

94. Birth

95. After
birth

97. Sexual reproduction
• The egg cell begins to divide forming a ball of
cells
Stem cells – have the potential
to become any type of cell.
http://www.medicalnewstoday.
com/info/stem_cell/

98. Sexual reproduction
• It may take several days to reach the uterus
and be implanted in the soft lining. It is now an
embryo.

99. Sexual reproduction
• Finger–like projections grow into the uterus
forming a plate like structure called the
placenta.

100. Sexual reproduction
• The umbilical cord joins the fetus to the
placenta.

101. • The placenta develops. This is an organ containing blood vessels that run very
near to those of the mother.
• The placenta is connected to the foetus by the umbilical cord.
• Oxygen and food pass from the mother’s blood to the blood of the foetus.
• Carbon dioxide and waste pass from the foetus to the mother.
• Some harmful substances can cross the placenta.
The
Placenta

102. The placenta
• In the placenta food and oxygen diffuse from
the mother’s blood to the fetus’ blood, and
carbon dioxide and waste products diffuse the
other way.

103. The placenta
• In the placenta the blood of the fetus flows
close to the blood of the mother, but they do
not mix.
Why?

104. The placenta
• In the placenta the blood of the fetus flows
close to the blood of the mother, but they do
not mix.
• The mother’s blood under higher pressure
would burst the vessels in the developing fetus.
• They may have different blood types.

105. Amnion
• The fetus is surrounded by a fluid-filled sac
(amnion) filled with amnionic fluid. This
protects the baby.

106. Week 8
• Baby's spinal column are beginning to form around
week 5
• Heart is beating
• Lungs are formed
• Eyes and ears are developing
• All internal organs are in
place by week 8
• Genital organs are visible

107. Week 12
• Inner ear, external ears, eyes,
mouth and nose are developing
• Heart is pumping blood
to all parts of the body

108. Week 16
• Baby is now completely formed
• From now on, growth will be rapid
• Heartbeat can be heard with ultrasound
• Baby's weight has more than doubled from week 15
to week 16
• Baby is moving quite vigorously

109. Week 20
• Baby is covered in fine hair
• Muscles are developing rapidly
• Teeth are beginning to form
• Hair is growing on baby's head
• Baby is very active

110. Week 24
• Baby can suck its thumb
• Baby can hiccup and cough
• Baby weighs just over 1 pound
With special care I could survive if born
now

111. Week 28
• Baby's lungs are mature
• Fat is starting to accumulate
• Baby weighs approximately
2 pounds

112. Week 32
• Most babies are in the head
down position
• Baby weighs
approximately 3.5 pounds

113. Week 36
• Baby continues
to gain weight
• The irises of the eyes
are now blue
• Baby weighs
approximately 5 pounds

114. Week 40
• Most of the vernix on
the baby is gone
• Baby's eyes are open
and it can distinguish light

115. Time to leave!

116. The Birthing Process
1. A few days, or weeks, before the birth, the foetus usually turns so that its head is by the
cervix (the entrance to the uterus). This is the position in which birth is most
straightforward.
2. Birth is a process which is started by hormones. These are chemical messengers which are
produced by different parts of the mother and baby.
3. Hormones cause the muscles in the walls of the uterus to start contracting. These
contractions became more regular and stronger as the time of birth approaches.
4. The cervix starts to open and when the opening is large enough the head of the baby
passes into the vagina.
5. The amnion splits and the watery amniotic fluid runs out.
6. Powerful muscles in the uterus wall push the baby down the vagina until it is born.
7. This process can take anything from a few minutes to several hours.
8. The newborn baby is usually weighed and measured before being handed to its mother.
9. After the baby has been born, the uterus continues to contract until the placenta
(afterbirth) has passed out of the mother's body.

117. Name of Part Job of Part
Protects the baby from bumps
Joins the placenta to the baby
Supplies the baby with food
and oxygen
Place that feeds and shelters
the baby
The developing baby
The baby is pushed out here
Ring of muscle at entrance of
uterus which widens to let the
baby out.

118. Sexually transmitted disease

119. • STDs refer to illnesses that are usually
transmitted through sexual contact.
• These diseases can also be picked up in other
ways – like through infected needles, Some
children may inherit from mothers.
• Only proper STD testing can confirm.

120. • Primarily, STDs are being transmitted through
the exchange of saliva, venereal fluids, skin or
mucosal contact
• While some diseases are more easily
transmissible than others, most of them are
contagious enough to make it highly likely to
get infected in the case of having unprotected
sex with an infected person

121. STDs can be categorized based on the
cause of the illness
• Bacterial STDs are caused through the transmittal
of a bacteria. chlamydia, Gonorrhoea, Syphilis or
urinary tract infections.
• Fungal STDs refer to diseases that are caused by
fungi, such as Thrush.
• Viral STDs are the most notorious category,
including HIV, Viral hepatitis ,Herpes (oral or
genital)
• Parasites like Scabies and Crab louse.
• Protozoal STDs like Trichomniasis.

123. Bacterial - Gonorrhoea

124. Fungal - Thrush

125. Viral - Herpes

126. Parasites - Crabs

133. HIV
• http://www.youtube.com/watch?v=kIISXIOJW
BE

134. How Does HIV Affect the Immune System?
The first stage of HIV contraction is acute HIV infection. Since HIV is comprised of both
RNA and DNA elements, it has the ability to directly infect human cells and utilize their
components (in one of the 46 chromosomes) to replicate parts of the HIV structure.
The immune system, for all intents and purposes, is comprised of two primary cell
types: the B-cell and the T-cell. The two particular types of T-cell, helper and cytotoxic,
are affected in distinct ways by the virus, leading to a constant struggle between virus-
replication efforts and immune system T-cell reproduction.
The helper T-cells (CD4) function as the body's alarm system to initiate the cytotoxic
cells, which attack and kill those cells in the body infected by the intruding virus.
Because HIV attacks these helper T-cells immediately upon contraction, the immune
system response capabilities gradually deteriorate throughout the duration of
infection. As the body regenerates new T-cells, the reproducing HIV strands will target,
infect and kill the new immune system elements.
The fight turns into a cycle of cell infection, death and reproduction for
approximately 10 years until the body is so severely weakened by an inability to
produce T-cells that it succumbs to weak viral and bacterial organisms (not HIV) that
are normally simple work for the base human immune system. Once this has occurred,
the ensuing condition is commonly known as AIDS, or acquired immunodeficiency
syndrome