Sexual reproduction in mammals
maureen141
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Nov 20, 2016
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About This Presentation
Reproduction ensures the continuation of a species.
Slide Content
U13: Sexual
Reproduction
in humans
Part 1:
The Male Reproductive system:
Structure and function
To be used with U 13 Lesson 2
Reproduction
in humans
Part 1:
The Male Reproductive system:
Structure and function
To be used with U 13 Lesson 2
The male reproductive system
Sexual reproduction is the means by which
humans produce their offspring.
Humans are perhaps unique in that sexual
intercourse is not only an act of potential
reproduction but also gives pleasure.
The male organs of the reproductive system are
structured to produce, temporarily store and
periodically release (ejaculate) male gametes
called spermatozoa (sperm, for short!).
Sexual reproduction is the means by which
humans produce their offspring.
Humans are perhaps unique in that sexual
intercourse is not only an act of potential
reproduction but also gives pleasure.
The male organs of the reproductive system are
structured to produce, temporarily store and
periodically release (ejaculate) male gametes
called spermatozoa (sperm, for short!).
Objectives
When you complete this lesson, you
should be able to :
1.use labeled diagrams to describe the
arrangement of the organs of the male
reproductive system.
2.annotate diagrams to show their
functions.
When you complete this lesson, you
should be able to :
1.use labeled diagrams to describe the
arrangement of the organs of the male
reproductive system.
2.annotate diagrams to show their
functions.
The male reproductive system
Some organs are visible from outside the body,
and some are contained inside the abdominal
cavity. The organs only mature and become
functional when puberty starts.
The diagrams in the following slides illustrate the
male reproductive system. An accessory gland is
labeled on the next slide.
What is it? (The video clip below should help!)
http://www.healthline.com/vpbody/reproductive-male
Some organs are visible from outside the body,
and some are contained inside the abdominal
cavity. The organs only mature and become
functional when puberty starts.
The diagrams in the following slides illustrate the
male reproductive system. An accessory gland is
labeled on the next slide.
What is it? (The video clip below should help!)
http://www.healthline.com/vpbody/reproductive-male
The male reproductive system
http://www.cartage.org.lb/en/themes/Sciences/LifeScience/GeneralBiology/Physiology/Reproduct
iveSystem/HumanReproduction/malerepro_1.gif
http://www.cartage.org.lb/en/themes/Sciences/LifeScience/GeneralBiology/Physiology/Reproduct
iveSystem/HumanReproduction/malerepro_1.gif
Male reproductive organs (Side view)
http://www.web-
books.com/eLibrary/Medicine/Physiology/Reproductive/repdt_male.jpg
http://www.web-
books.com/eLibrary/Medicine/Physiology/Reproductive/repdt_male.jpg
Testosterone
•You no doubt remember that you learnt about
the endocrine system?
Which endocrine gland produces the hormone
testosterone?
•Yes, the testes.
•Let’s review the function of testosterone.
•You no doubt remember that you learnt about
the endocrine system?
Which endocrine gland produces the hormone
testosterone?
•Yes, the testes.
•Let’s review the function of testosterone.
The role of testosterone
•Testosterone is known as the ‘male hormone’.
•It is produced by the testes.
•The testes are stimulated into action by
Follicle Stimulating Hormone (FSH) produced
by the pituitary gland.
•This happens even before birth.
•Testosterone is produced in even larger
quantities as soon as a male hits puberty.
•Testosterone is known as the ‘male hormone’.
•It is produced by the testes.
•The testes are stimulated into action by
Follicle Stimulating Hormone (FSH) produced
by the pituitary gland.
•This happens even before birth.
•Testosterone is produced in even larger
quantities as soon as a male hits puberty.
The role of testosterone cont’d
•Testosterone controls the development of
secondary sexual characteristics.
•What are secondary sexual characteristics?
•These are the physical and emotional
characteristics that distinguishes a male from
a female.
•Do you now realize why testosterone is called
the male hormone?
•Testosterone controls the development of
secondary sexual characteristics.
•What are secondary sexual characteristics?
•These are the physical and emotional
characteristics that distinguishes a male from
a female.
•Do you now realize why testosterone is called
the male hormone?
Male secondary sexual
characteristics
•Let’s look at these visible secondary sexual
characteristics. Most are obvious in males
around you, so you should be able to state
them correctly.
•Go through the following slides to see if you
were correct.
characteristics
•Let’s look at these visible secondary sexual
characteristics. Most are obvious in males
around you, so you should be able to state
them correctly.
•Go through the following slides to see if you
were correct.
Male secondary sexual
characteristics cont’d
•An early sign is that deepening of the voice
starts, but the voice frequently goes back to
being high-pitched or ‘breaks’.
•It becomes possible to ejaculate semen, and
this frequently occurs as ‘wet dreams’.
•Let’s look at some other characteristics.
characteristics cont’d
•An early sign is that deepening of the voice
starts, but the voice frequently goes back to
being high-pitched or ‘breaks’.
•It becomes possible to ejaculate semen, and
this frequently occurs as ‘wet dreams’.
•Let’s look at some other characteristics.
Growth of facial hair starts at puberty.
The growth of facial hair is due to the action of testosterone.
This hair tends to be much coarser than hair on the head.
http://i.ehow.com/im
ages/GlobalPhoto/A
rticles/5471404/390
269-main_Full.jpg
The growth of facial hair is due to the action of testosterone.
This hair tends to be much coarser than hair on the head.
http://i.ehow.com/im
ages/GlobalPhoto/A
rticles/5471404/390
269-main_Full.jpg
Chest and underarm or axillary hairs grow.
This hair growth is also due to the action of testosterone.
http://static.howstuffw
orks.com/gif/human-
body-hair-2.jpg
This hair growth is also due to the action of testosterone.
http://static.howstuffw
orks.com/gif/human-
body-hair-2.jpg
Pubic hair grows.
Growth of
penis and testes
occurs.
Growth of pubic hair and enlargement of the genitals is
caused by the action of testosterone
http://www.healthofchildren.com/images/gech_0001_0003_0_img0221.jpg
Growth of
penis and testes
occurs.
Growth of pubic hair and enlargement of the genitals is
caused by the action of testosterone
http://www.healthofchildren.com/images/gech_0001_0003_0_img0221.jpg
Broadening of the shoulders and development of
muscles increase as a boy becomes a man.
.
http://www.abpischools.org.uk/res/coResourceImport/modules/hormones/en-images/male.jpg
muscles increase as a boy becomes a man.
.
http://www.abpischools.org.uk/res/coResourceImport/modules/hormones/en-images/male.jpg
•The testes enlarge as sperm production
starts.
•The penis also enlarges to facilitate
sexual intercourse during copulation in
which spermatozoa in the semen are
ejaculated into the female’s vagina.
Importance of secondary sexual
characteristics
starts.
•The penis also enlarges to facilitate
sexual intercourse during copulation in
which spermatozoa in the semen are
ejaculated into the female’s vagina.
Importance of secondary sexual
characteristics
To Think About!
•No doubt young women would agree
that all these new secondary
characteristics make males more
attractive! So, these characteristics
attract potential partners to ensure
sexual reproduction and the diversity
that accompanies the production of
offspring arising from that activity.
•No doubt young women would agree
that all these new secondary
characteristics make males more
attractive! So, these characteristics
attract potential partners to ensure
sexual reproduction and the diversity
that accompanies the production of
offspring arising from that activity.
To Think About!
•Remember however, that these new
characteristics will remain for a long
time and are common among all males,
so…. there is no need to rush into
finding a partner and beginning to
‘have sex’!
•Remember however, that these new
characteristics will remain for a long
time and are common among all males,
so…. there is no need to rush into
finding a partner and beginning to
‘have sex’!
•Go have a talk with a trusted relative,
counsellor or your parent/guardian
about the pros and cons of ‘having sex’
at your age.
•Remember… if you ‘have sex’ even
once, you could yourself become a
parent or contract a disease e.g.
HIV/AIDS.
Are you ready for either of those?
counsellor or your parent/guardian
about the pros and cons of ‘having sex’
at your age.
•Remember… if you ‘have sex’ even
once, you could yourself become a
parent or contract a disease e.g.
HIV/AIDS.
Are you ready for either of those?
U 13: Sexual Reproduction
in Humans
Part 2:
The Female Reproductive System
•Structure and function
To be used with U 13 Lesson 3
in Humans
Part 2:
The Female Reproductive System
•Structure and function
To be used with U 13 Lesson 3
Objectives
When you complete this lesson, you should be
able to:
1.use annotated diagrams to describe the
structure and functions of the organs of the
human female reproductive system.
2.show greater appreciation for female
reproductive health.
When you complete this lesson, you should be
able to:
1.use annotated diagrams to describe the
structure and functions of the organs of the
human female reproductive system.
2.show greater appreciation for female
reproductive health.
Functions of the adult Female
Reproductive System
•Produce a mature egg each month, starting at
puberty.
•Facilitate the deposit of spermatozoa and their
transit to meet the egg.
•Prepare for and accommodate the implant of a
fertilized egg, and its complex development over
roughly nine months.
•Give birth to a new human being.
What an absolutely amazing system!
Reproductive System
•Produce a mature egg each month, starting at
puberty.
•Facilitate the deposit of spermatozoa and their
transit to meet the egg.
•Prepare for and accommodate the implant of a
fertilized egg, and its complex development over
roughly nine months.
•Give birth to a new human being.
What an absolutely amazing system!
The female reproductive system
•Each part is so structured to carry out those
specific functions and all the parts work
together to ensure that a female can produce
offspring to continue the species.
•Because of its important function, care must
be taken to practice proper hygiene, to take
measures to prevent STDs and to have a diet
that will keep the entire body healthy.
•The diagrams in the following slides illustrate
the female reproductive system.
•Each part is so structured to carry out those
specific functions and all the parts work
together to ensure that a female can produce
offspring to continue the species.
•Because of its important function, care must
be taken to practice proper hygiene, to take
measures to prevent STDs and to have a diet
that will keep the entire body healthy.
•The diagrams in the following slides illustrate
the female reproductive system.
Location and external parts of the
female reproductive system
http://www.cartage.org.lb/en/themes/Sciences/LifeScience/GeneralBiology/Physiology/ReproductiveSystem/HumanRepro
duction/femalerepro_1.gif
female reproductive system
http://www.cartage.org.lb/en/themes/Sciences/LifeScience/GeneralBiology/Physiology/ReproductiveSystem/HumanRepro
duction/femalerepro_1.gif
Female reproductive system - Front view
http://www.glogster.com/media/1/4/7/18/4071820.jpg
http://www.glogster.com/media/1/4/7/18/4071820.jpg
Female reproductive system - Side view
http://www.tqnyc.org/2006/NYC063547//images/femalereproductivesystem.jpg
http://www.tqnyc.org/2006/NYC063547//images/femalereproductivesystem.jpg
Female Secondary Sexual
Characteristics
•Having already explored the endocrine
system, you know that females have an
equivalent hormone to testosterone.
•This hormone is oestrogen.
•It also controls development of secondary
sexual characteristics.
Think about what happened in your own body
or what you observed in a female in class/at
home, then list the characteristics.
Characteristics
•Having already explored the endocrine
system, you know that females have an
equivalent hormone to testosterone.
•This hormone is oestrogen.
•It also controls development of secondary
sexual characteristics.
Think about what happened in your own body
or what you observed in a female in class/at
home, then list the characteristics.
Secondary sexual characteristics in
females
Here’s a summary of what you should have:
•Broadening and curving of hips
•Enlargement of breasts
•Enlargement of reproductive organs
•Growth of underarm and pubic hair
•Menstruation begins
All will not appear at the same time for all
females since the age of puberty varies.
females
Here’s a summary of what you should have:
•Broadening and curving of hips
•Enlargement of breasts
•Enlargement of reproductive organs
•Growth of underarm and pubic hair
•Menstruation begins
All will not appear at the same time for all
females since the age of puberty varies.
All the changes
in the diagrams
are due to
Oestrogen.
http://www.abpischools.org.uk/res/coResourceImport/modules/hormones/en-images/female.jpg
in the diagrams
are due to
Oestrogen.
http://www.abpischools.org.uk/res/coResourceImport/modules/hormones/en-images/female.jpg
Importance of secondary sexual
characteristics
These changes ensure the continuation of the
species.
•Menstruation occurs because the
reproductive system is now functioning; it
shows that an egg was produced each month
but was not fertilized.
•The breasts enlarge to enable milk production
for possibly nursing a baby.
•The hips enlarge to facilitate child bearing.
characteristics
These changes ensure the continuation of the
species.
•Menstruation occurs because the
reproductive system is now functioning; it
shows that an egg was produced each month
but was not fertilized.
•The breasts enlarge to enable milk production
for possibly nursing a baby.
•The hips enlarge to facilitate child bearing.
U 13: The Menstrual Cycle
To be used with U 13 Les 4
Females are saying….
Mummy.. remember
to buy pads for me,
OKay?
I just feel bloated
and so tired
when my periods
come!
I hope I
don’t get
headaches
and vomit
this month!
Oh Thank God!
That means I’m not
pregnant! Jerry and
I just not ready for a
second child now.
To be used with U 13 Les 4
Females are saying….
Mummy.. remember
to buy pads for me,
OKay?
I just feel bloated
and so tired
when my periods
come!
I hope I
don’t get
headaches
and vomit
this month!
Oh Thank God!
That means I’m not
pregnant! Jerry and
I just not ready for a
second child now.
Objectives
When you finish, you should be able to:
1.explain why females have monthly menses.
2.state the functions of hormones in the
menstrual cycle.
When you finish, you should be able to:
1.explain why females have monthly menses.
2.state the functions of hormones in the
menstrual cycle.
The Menstrual Cycle
•Normal, healthy females such as members of
this class should be ‘having a period’ each
month. What is it? Why does it happen?
•A ‘period’ is the shedding of the lining or
endometrium of the uterus wall.
•It happens because fertilization and
subsequent pregnancy did not occur.
•Having a period is part of a cycle which is
controlled by several hormones.
•Normal, healthy females such as members of
this class should be ‘having a period’ each
month. What is it? Why does it happen?
•A ‘period’ is the shedding of the lining or
endometrium of the uterus wall.
•It happens because fertilization and
subsequent pregnancy did not occur.
•Having a period is part of a cycle which is
controlled by several hormones.
The menstrual cycle cont’d
•The first day of a female’s period or menses
marks the first day (Day 1) of the menstrual
cycle.
•This cycle normally spans between 21 to 28
days.
•Let’s look at the hormones involved and what
they do. They are FSH or Follicle Stimulating
Hormone, LH = Luteinizing Hormone and
Progesterone.
•The first day of a female’s period or menses
marks the first day (Day 1) of the menstrual
cycle.
•This cycle normally spans between 21 to 28
days.
•Let’s look at the hormones involved and what
they do. They are FSH or Follicle Stimulating
Hormone, LH = Luteinizing Hormone and
Progesterone.
The menstrual cycle cont’d
•Starting from day 1 of the cycle, the pituitary
gland secretes FSH.
•This causes a Graafian follicle to develop.
•As the follicle develops in the ovary, the ovary
secretes oestrogen.
•Oestrogen causes the cells of the endometrial
wall to gradually become filled with blood and
fluid.
•Starting from day 1 of the cycle, the pituitary
gland secretes FSH.
•This causes a Graafian follicle to develop.
•As the follicle develops in the ovary, the ovary
secretes oestrogen.
•Oestrogen causes the cells of the endometrial
wall to gradually become filled with blood and
fluid.
The menstrual cycle cont’d
•At about day 14 another pituitary hormone,
LH is secreted in high concentration.
•LH causes the Graafian follicle to rupture
releasing the egg. This is ovulation.
•The period before ovulation is the Follicular
Phase and includes menstruation.
•The LH also causes the remains of the follicle
to be converted to the corpus luteum or
yellow body. This is now the Luteal Phase
•At about day 14 another pituitary hormone,
LH is secreted in high concentration.
•LH causes the Graafian follicle to rupture
releasing the egg. This is ovulation.
•The period before ovulation is the Follicular
Phase and includes menstruation.
•The LH also causes the remains of the follicle
to be converted to the corpus luteum or
yellow body. This is now the Luteal Phase
The menstrual cycle cont’d
•The corpus luteum secretes the hormone
progesterone.
•Progesterone maintains the thickness of the
lining of the uterus (in case of fertilization).
•Have you ever heard of ‘pregnancy hormone’?
It is progesterone.
Pay keen attention as your teacher guides you
through the next slide.
Answer the related questions in your SIM (pg 5)
about concentration of various hormones and
endometrial thickness.
•The corpus luteum secretes the hormone
progesterone.
•Progesterone maintains the thickness of the
lining of the uterus (in case of fertilization).
•Have you ever heard of ‘pregnancy hormone’?
It is progesterone.
Pay keen attention as your teacher guides you
through the next slide.
Answer the related questions in your SIM (pg 5)
about concentration of various hormones and
endometrial thickness.
Graph showing the relationship between hormone
concentration and endometrial thickness
http://images.google.com.jm/imgres?
imgurl=http://8e.devbio.com/images/ch19/11.HMEM.01.thumb.jpg&imgrefurl=http://www.podnova.com/channel/174193/episode/41/&usg=__0anawtqmg5QmXU3i0IZO7
CYaDrc=&h=450&w=392&sz=62&hl=en&start=2&um=1&itbs=1&tbnid=KdZPFIhFasqFTM:&tbnh=127&tbnw=111&prev=/images%3Fq%3Dgraph%2Bof%2Bmenstrual
%2Bcycle%26hl%3Den%26rlz%3D1T4DMUS_enJM290JM296%26sa%3DN%26um%3D1
concentration and endometrial thickness
http://images.google.com.jm/imgres?
imgurl=http://8e.devbio.com/images/ch19/11.HMEM.01.thumb.jpg&imgrefurl=http://www.podnova.com/channel/174193/episode/41/&usg=__0anawtqmg5QmXU3i0IZO7
CYaDrc=&h=450&w=392&sz=62&hl=en&start=2&um=1&itbs=1&tbnid=KdZPFIhFasqFTM:&tbnh=127&tbnw=111&prev=/images%3Fq%3Dgraph%2Bof%2Bmenstrual
%2Bcycle%26hl%3Den%26rlz%3D1T4DMUS_enJM290JM296%26sa%3DN%26um%3D1
The menstrual cycle cont’d
•Progesterone also causes the breasts to
enlarge and become tender.
•It causes water retention which is
responsible for the bloating associated with
periods.
•In addition, the female might experience
various changes such as: cravings for specific
foods, fatigue, headaches, nausea, sensitivity
and she might become easily emotional.
•Progesterone also causes the breasts to
enlarge and become tender.
•It causes water retention which is
responsible for the bloating associated with
periods.
•In addition, the female might experience
various changes such as: cravings for specific
foods, fatigue, headaches, nausea, sensitivity
and she might become easily emotional.
The menstrual cycle cont’d
•The uterus wall is thickened in
preparation for a possible embryo to be
embedded and for pregnancy to result.
•The egg can live for just about 24 hours
after ovulation.
•If no fertilization occurs, the egg dies.
•The uterus wall is thickened in
preparation for a possible embryo to be
embedded and for pregnancy to result.
•The egg can live for just about 24 hours
after ovulation.
•If no fertilization occurs, the egg dies.
The menstrual cycle cont’d
•If there is no pregnancy, the
progesterone level falls and the uterus
wall breaks down and passes out of the
vagina as ‘a period’ or the menses, with
small clumps of the endometrial lining
and blood.
•If there is no pregnancy, the
progesterone level falls and the uterus
wall breaks down and passes out of the
vagina as ‘a period’ or the menses, with
small clumps of the endometrial lining
and blood.
To Think About
Now that you have been reintroduced to the
hormones that control the menstrual cycle, go
back to the lessons you did already on
hormones and go through them again to make
sure you fully understand the many ways that
hormones influence growth and development.
Now that you have been reintroduced to the
hormones that control the menstrual cycle, go
back to the lessons you did already on
hormones and go through them again to make
sure you fully understand the many ways that
hormones influence growth and development.
U 13: Fertilization
To be used with U 13 Lesson 5
•http://www.tutorvista.com/content/science/science-ii/reproduction/fertilisation.php
To be used with U 13 Lesson 5
•http://www.tutorvista.com/content/science/science-ii/reproduction/fertilisation.php
Objectives
On completion you should be able to:
1.define and differentiate between
fertlization and implantation.
2.define and differentiate between a zygote
and an embryo.
3.explain how multiple births, identical and
fraternal twins are likely to occur.
On completion you should be able to:
1.define and differentiate between
fertlization and implantation.
2.define and differentiate between a zygote
and an embryo.
3.explain how multiple births, identical and
fraternal twins are likely to occur.
Leading up to Fertilization
•Perhaps you might be wondering: ‘How does
an egg become fertilized?’
•Let’s look at the natural method of
fertilization.
•During sexual arousal, the penis becomes
erect. This facilitates intercourse, in which the
erect penis is inserted into the vagina.
•Stimulation of the penis from rhythmic
movements during intercourse causes
ejaculation.
•Perhaps you might be wondering: ‘How does
an egg become fertilized?’
•Let’s look at the natural method of
fertilization.
•During sexual arousal, the penis becomes
erect. This facilitates intercourse, in which the
erect penis is inserted into the vagina.
•Stimulation of the penis from rhythmic
movements during intercourse causes
ejaculation.
Fertilization
•Ejaculation causes millions of sperms in semen
to be released into the vagina.
•These swim up through the cervix and womb
and enter the fallopian tube.
•Near the top they might meet/surround the
egg that was released during ovulation.
•If there is an egg, one sperm enters the egg
and both haploid nuclei fuse.
•A membrane is formed to prevent entry of
another sperm.
•Ejaculation causes millions of sperms in semen
to be released into the vagina.
•These swim up through the cervix and womb
and enter the fallopian tube.
•Near the top they might meet/surround the
egg that was released during ovulation.
•If there is an egg, one sperm enters the egg
and both haploid nuclei fuse.
•A membrane is formed to prevent entry of
another sperm.
Illustration of the steps involved in fertilization.
http://images.google.com.jm/imgres?
imgurl=http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2005/Champa
loux/fertilization.jpg&imgrefurl=http://www.bio.davidson.edu/Courses/Molbio/MolStude
nts/spring2005/Champaloux/fourth.html&usg=__qfNE_wr7Zs4viL_ERV_yKnnbtAU=&h
=419&w=574&sz=19&hl=en&start=1&um=1&itbs=1&tbnid=cVGNeljSDv6rBM:&tbnh=9
8&tbnw=134&prev=/images%3Fq%3Dfertilization%26hl%3Den%26rlz
%3D1T4DMUS_enJM290JM296%26sa%3DN%26um%3D1
http://images.google.com.jm/imgres?
imgurl=http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2005/Champa
loux/fertilization.jpg&imgrefurl=http://www.bio.davidson.edu/Courses/Molbio/MolStude
nts/spring2005/Champaloux/fourth.html&usg=__qfNE_wr7Zs4viL_ERV_yKnnbtAU=&h
=419&w=574&sz=19&hl=en&start=1&um=1&itbs=1&tbnid=cVGNeljSDv6rBM:&tbnh=9
8&tbnw=134&prev=/images%3Fq%3Dfertilization%26hl%3Den%26rlz
%3D1T4DMUS_enJM290JM296%26sa%3DN%26um%3D1
Fertilization cont’d
•A zygote is formed from fertilization.
What is the chromosome number of the
zygote?
•Yes! The zygote is diploid.
This zygote will grow into an embryo. Which
nuclear division do you think is involved?
•Correct again -- mitosis.
•A zygote is formed from fertilization.
What is the chromosome number of the
zygote?
•Yes! The zygote is diploid.
This zygote will grow into an embryo. Which
nuclear division do you think is involved?
•Correct again -- mitosis.
Twins and Multiples
•Sometimes more that one egg matures and
ovulates, and they may be fertilized
separately. This can result in fraternal twins
or fraternal multiples who can be either same
sex or different-sex children.
•If the fertilized egg separates as it is
undergoing its early divisions, identical twins
and identical multiples could result.
Identical twins/multiples are always the same
sex. Tell your teacher why this is so.
•Sometimes more that one egg matures and
ovulates, and they may be fertilized
separately. This can result in fraternal twins
or fraternal multiples who can be either same
sex or different-sex children.
•If the fertilized egg separates as it is
undergoing its early divisions, identical twins
and identical multiples could result.
Identical twins/multiples are always the same
sex. Tell your teacher why this is so.
“Twincredibles”
•Go to this website to see and read about
two incredible sets of twins!
http://www.thesun.co.uk/sol/homepage/news/article2082429.ece
Is each set an identical pair or not?
Explain how you think each set of twins
came about!
•Go to this website to see and read about
two incredible sets of twins!
http://www.thesun.co.uk/sol/homepage/news/article2082429.ece
Is each set an identical pair or not?
Explain how you think each set of twins
came about!
Fertilization and Implantation
•As the zygote divides by mitosis an embryo is
formed.
•As it divides, the ball of cells moves down the
Fallopian tube into the uterus.
Now think back to the menstrual cycle.
Describe how you would expect the
endometrium to be. Give a reason for your
answer.
•As the zygote divides by mitosis an embryo is
formed.
•As it divides, the ball of cells moves down the
Fallopian tube into the uterus.
Now think back to the menstrual cycle.
Describe how you would expect the
endometrium to be. Give a reason for your
answer.
Fertilization and implantation
cont’d
•Yes…You are correct again! The endometrial wall
is thickened with blood due to the action of
oestrogen secreted as the follicle developed.
Progesterone from the corpus luteum is also
responsible.
•The embryo sinks and becomes embedded in this
nice soft bed in the endometrial wall.
This is implantation.
Look carefully at the next slide that show it.
cont’d
•Yes…You are correct again! The endometrial wall
is thickened with blood due to the action of
oestrogen secreted as the follicle developed.
Progesterone from the corpus luteum is also
responsible.
•The embryo sinks and becomes embedded in this
nice soft bed in the endometrial wall.
This is implantation.
Look carefully at the next slide that show it.
Fertilization and implantation
cont’d
http://images.google.com.jm/imgres?
imgurl=http://www.mayoclinic.com/images/image_popup/r7_fertilization.jpg&imgrefurl=http://www.mayoclinic.com/health/medical/IM02017&usg=__qhGj4Tcts6xssrDQn_2
pFfCtqCk=&h=306&w=400&sz=22&hl=en&start=3&um=1&itbs=1&tbnid=xwf4d6yuCZebSM:&tbnh=95&tbnw=124&prev=/images%3Fq%3Dfertilization%26hl%3Den%26rlz
%3D1T4DMUS_enJM290JM296%26sa%3DN%26um%3D1
cont’d
http://images.google.com.jm/imgres?
imgurl=http://www.mayoclinic.com/images/image_popup/r7_fertilization.jpg&imgrefurl=http://www.mayoclinic.com/health/medical/IM02017&usg=__qhGj4Tcts6xssrDQn_2
pFfCtqCk=&h=306&w=400&sz=22&hl=en&start=3&um=1&itbs=1&tbnid=xwf4d6yuCZebSM:&tbnh=95&tbnw=124&prev=/images%3Fq%3Dfertilization%26hl%3Den%26rlz
%3D1T4DMUS_enJM290JM296%26sa%3DN%26um%3D1
Summary
•Sexual reproduction is the production of
offspring from two parents. It involves:
1.Meiosis - the special cell division that makes
haploid gametes (eggs and sperms).
2.Ovulation – release of an egg from the ovary.
3.Sexual intercourse with Ejaculation of sperms.
4.Fertilisation - fusion of two haploid gametes (an
egg and a sperm) to form a diploid zygote which
develops into an embryo.
5.Implantation of the embryo in the uterus.
6.Pregnancy/Gestation followed by Birth.
•Sexual reproduction is the production of
offspring from two parents. It involves:
1.Meiosis - the special cell division that makes
haploid gametes (eggs and sperms).
2.Ovulation – release of an egg from the ovary.
3.Sexual intercourse with Ejaculation of sperms.
4.Fertilisation - fusion of two haploid gametes (an
egg and a sperm) to form a diploid zygote which
develops into an embryo.
5.Implantation of the embryo in the uterus.
6.Pregnancy/Gestation followed by Birth.
U 13: Lesson 6
Pregnancy
and Birth
.
http://www.tutorvista.com/content/science/science-ii/reproduction/fertilisation.php
Photopraph at lower right © K.Muir 2008, with kind permission
Pregnancy
and Birth
.
http://www.tutorvista.com/content/science/science-ii/reproduction/fertilisation.php
Photopraph at lower right © K.Muir 2008, with kind permission
Objectives
When you finish, you should be able to:
1.describe the development of the
embryo (gestation) in humans.
2.list the steps that result in birth or
parturition.
When you finish, you should be able to:
1.describe the development of the
embryo (gestation) in humans.
2.list the steps that result in birth or
parturition.
Pregnancy
•Pregnancy starts
after fertilization
occurs when the new
embryo implants
itself in the lining
of the uterus wall
and begins to
develop.
•Pregnancy starts
after fertilization
occurs when the new
embryo implants
itself in the lining
of the uterus wall
and begins to
develop.
Pregnancy cont’d
•I am sure you have been associated with
pregnant persons.
So, what are the changes that occur during
pregnancy?
•No doubt you are thinking of: swelling of
feet… nose/face looking fat… abdomen
getting larger…
But, what else happens?
•I am sure you have been associated with
pregnant persons.
So, what are the changes that occur during
pregnancy?
•No doubt you are thinking of: swelling of
feet… nose/face looking fat… abdomen
getting larger…
But, what else happens?
Some changes during pregnancy
•Nausea and vomiting usually occur, due to the
increase in progesterone levels. They are
among the first changes that occur in
pregnancy.
•The menses cease.
•There may be lethargy/tiredness.
•Breasts and abdomen begin to enlarge.
•There may be mood swings and food cravings
or food rejections.
•Nausea and vomiting usually occur, due to the
increase in progesterone levels. They are
among the first changes that occur in
pregnancy.
•The menses cease.
•There may be lethargy/tiredness.
•Breasts and abdomen begin to enlarge.
•There may be mood swings and food cravings
or food rejections.
Pregnancy cont’d
•Many changes also
take place in the
embryo! Many
structures can be
recognized by 6 weeks.
•The foetus is attached
to the placenta by the
umbilical cord.
http://www.mydr.com.au/babies-pregnancy/
baby-development-in-the-womb
•Many changes also
take place in the
embryo! Many
structures can be
recognized by 6 weeks.
•The foetus is attached
to the placenta by the
umbilical cord.
http://www.mydr.com.au/babies-pregnancy/
baby-development-in-the-womb
Pregnancy changes cont’d
•But what causes these changes?
•Yes, hormones and in particular, the
‘pregnancy hormone’ which is progesterone.
•Where does the progesterone come from?
•You would remember that the corpus luteum
secretes progesterone.
•However, the majority of the progesterone
secreted during pregnancy is not done by the
corpus luteum.
•But what causes these changes?
•Yes, hormones and in particular, the
‘pregnancy hormone’ which is progesterone.
•Where does the progesterone come from?
•You would remember that the corpus luteum
secretes progesterone.
•However, the majority of the progesterone
secreted during pregnancy is not done by the
corpus luteum.
Pregnancy changes cont’d
•After implantation, some of the dividing cells
form fingerlike projections that dig into the
endometrium of the uterine wall.
•These fingerlike projections along with the
mother’s tissue that surrounds them form the
placenta.
•The placenta performs several roles including
an endocrine one; it secretes progesterone.
•After implantation, some of the dividing cells
form fingerlike projections that dig into the
endometrium of the uterine wall.
•These fingerlike projections along with the
mother’s tissue that surrounds them form the
placenta.
•The placenta performs several roles including
an endocrine one; it secretes progesterone.
Pregnancy changes cont’d
•The placenta facilitates the exchange of
material between the mother and
foetus.
•Nutrients and oxygen diffuse from the
mother to the foetus via the umbilical
cord; waste from the foetus diffuses in
the opposite direction.
•The placenta is also a barrier to some
pathogens and harmful materials.
•The placenta facilitates the exchange of
material between the mother and
foetus.
•Nutrients and oxygen diffuse from the
mother to the foetus via the umbilical
cord; waste from the foetus diffuses in
the opposite direction.
•The placenta is also a barrier to some
pathogens and harmful materials.
Pregnancy changes cont’d
•So…. back to the pregnancy changes.
Can you suggest the importance of the changes
in the mother’s body that occur during
pregnancy? Click CheckCheck for the answer:
•(The breasts enlarge as the mammary glands
expand to facilitate milk production.
•The uterine wall actually grows new cells so
that it can enlarge to hold the foetus.
continued…
•So…. back to the pregnancy changes.
Can you suggest the importance of the changes
in the mother’s body that occur during
pregnancy? Click CheckCheck for the answer:
•(The breasts enlarge as the mammary glands
expand to facilitate milk production.
•The uterine wall actually grows new cells so
that it can enlarge to hold the foetus.
continued…
Pregnancy cont’d
Note enlarged breast, abdomen and uterus, also the
placenta and umbilical cord attached to foetus
http://health.howstuffworks.com/
pregnancy-pictures6.htm
Note enlarged breast, abdomen and uterus, also the
placenta and umbilical cord attached to foetus
http://health.howstuffworks.com/
pregnancy-pictures6.htm
Pregnancy changes cont’d
•The high levels of progesterone inhibit the
production of FSH and LH.
•This ensures that no more eggs are released
from the ovaries, so the menses stop
temporarily during pregnancy.
•The placenta continues to support the foetus
throughout gestation.
•The abdomen expands to facilitate the growth
of the foetus.)
•The high levels of progesterone inhibit the
production of FSH and LH.
•This ensures that no more eggs are released
from the ovaries, so the menses stop
temporarily during pregnancy.
•The placenta continues to support the foetus
throughout gestation.
•The abdomen expands to facilitate the growth
of the foetus.)
Pregnancy cont’d
http://www.mydr.com.au/babies-pregnancy/baby-s-development-in-the-womb
What is the function of amniotic fluid?
http://www.mydr.com.au/babies-pregnancy/baby-s-development-in-the-womb
What is the function of amniotic fluid?
Pregnancy cont’d
•Pregnancy normally
ends with labour and
birth.
•The foetus changes its
position so that during
birth the head will emerge
first (in normal births!).
http://www.mydr.com.au/babies-pregnancy/baby-
development-in-the-womb
•Pregnancy normally
ends with labour and
birth.
•The foetus changes its
position so that during
birth the head will emerge
first (in normal births!).
http://www.mydr.com.au/babies-pregnancy/baby-
development-in-the-womb
What ‘triggers’ Birth?
•Have you ever wondered what causes a
woman to go into labour? Hormones again??
•Yes, the onset of birth is controlled by a
hormone.
•When the foetus is large and it becomes
uncomfortable to remain in such a small space
(usually at 40 weeks), the foetus pushes
against the uterus.
•Have you ever wondered what causes a
woman to go into labour? Hormones again??
•Yes, the onset of birth is controlled by a
hormone.
•When the foetus is large and it becomes
uncomfortable to remain in such a small space
(usually at 40 weeks), the foetus pushes
against the uterus.
What ‘triggers’ Birth?
•Stretch receptors in the uterine wall start
to send signals to the brain (pituitary
gland).
•The pituitary stimulates the secretion of
the hormone oxytocin.
•The hormone stimulates the muscles of
the uterus to contract even further.
•Stretch receptors in the uterine wall start
to send signals to the brain (pituitary
gland).
•The pituitary stimulates the secretion of
the hormone oxytocin.
•The hormone stimulates the muscles of
the uterus to contract even further.
Birth cont’d
•So, the stimulus is enhanced and the
receptors in the distorted uterus
continue to send signals to the brain, and
it continues to stimulate the secretion of
even more oxytocin.
•This positive feedback loop is what
sustains contractions during labour.
•So, the stimulus is enhanced and the
receptors in the distorted uterus
continue to send signals to the brain, and
it continues to stimulate the secretion of
even more oxytocin.
•This positive feedback loop is what
sustains contractions during labour.
Birth cont’d
•The cervix and vagina
dilate and as the uterine
muscles continue to
contract, the baby is
pushed out, normally,
head first.
•The cervix and vagina
dilate and as the uterine
muscles continue to
contract, the baby is
pushed out, normally,
head first.
Note the umbilical cord still attached to the
new-born baby
http://www.medicinenet.com/stages_of_pregnancy_pictures_slideshow/article.htm
new-born baby
http://www.medicinenet.com/stages_of_pregnancy_pictures_slideshow/article.htm
Summary of Birth
•The signal that birth is imminent is that
uterine contractions start, the amniotic sac or
‘the water-bag’ bursts and the amniotic fluid
runs out as the ‘show of water’.
•Then the following stages of birth occur:
1. Dilation of the cervix and birth canal.
2. Delivery of the baby with its umbilical cord.
3. Cutting the umbilical cord.
4. Extrusion of the placenta as the ‘after-birth’.
•The signal that birth is imminent is that
uterine contractions start, the amniotic sac or
‘the water-bag’ bursts and the amniotic fluid
runs out as the ‘show of water’.
•Then the following stages of birth occur:
1. Dilation of the cervix and birth canal.
2. Delivery of the baby with its umbilical cord.
3. Cutting the umbilical cord.
4. Extrusion of the placenta as the ‘after-birth’.
After Birth
•After the baby is delivered, the placenta is
useless, so, it also is expelled by uterine
contractions. If not, it can cause complica-
tions that can lead to death of the mother.
•Oxytocin causes milk to be secreted from the
breasts especially under stimulation from
sucking by the baby.
•The vagina and uterus gradually contract.
•The menstrual cycle will start again later.
•After the baby is delivered, the placenta is
useless, so, it also is expelled by uterine
contractions. If not, it can cause complica-
tions that can lead to death of the mother.
•Oxytocin causes milk to be secreted from the
breasts especially under stimulation from
sucking by the baby.
•The vagina and uterus gradually contract.
•The menstrual cycle will start again later.
Parental Care
Oxytocin is believed to help create a bond
between mother and baby. Parental care
activities that follow the birth of a child are
very important. They involve both parents:
•feeding the baby with (breast) milk;
•carrying, cleaning and taking care of the baby
until s/he is able to do those things;
•imparting knowledge and teaching skills to
enable the baby to grow and develop into the
human being that can function normally on its
own.
Awesome tasks!!
Oxytocin is believed to help create a bond
between mother and baby. Parental care
activities that follow the birth of a child are
very important. They involve both parents:
•feeding the baby with (breast) milk;
•carrying, cleaning and taking care of the baby
until s/he is able to do those things;
•imparting knowledge and teaching skills to
enable the baby to grow and develop into the
human being that can function normally on its
own.
Awesome tasks!!
Basic life cycle of humans
http://www.nclark.net/Biology
http://www.nclark.net/Biology
Websites to visit
•http://www.healthline.com/vpvideo/stages-of-labor
•http://www.healthline.com/vpvideo/normal-birth
•http://www.healthline.com/vpvideo/stages-of-labor
•http://www.healthline.com/vpvideo/normal-birth
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