Integrated Science M3 Sexual Reproduction in Humans

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SEXUAL REPRODUCTION IN HUMANS
Integrated ScienceIntegrated Science  Module 3Module 3  Unit 7Unit 7  Lesson 7Lesson 7

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INTRODUCTION
 This slide presentation should help you to better understand the
inter-relatedness of various topics that you are studying.
 In the slide presentation, you will re-examine the changes that occur
during the life cycle that enable humans to carry out sexual
reproduction.You will see how hormones influence those changes
as well as the organs and processes, such as meiosis, that are
involved in the formation of gametes.
 You can access various subtopics by clicking on one of the buttons
above.

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OBJECTIVES
Having completed this slide presentation, you should be
able to:
 describe the changes that accompany puberty in males
and females.
 show understanding of the importance of meiosis in the
life cycle of humans.
 describe the structure and function of the male and
female reproductive system.
 research information and share ideas.

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1. Human Life Cycle
The life cycle diagram on the
left shows that both sexual
reproduction and growth occur.
Testis Ovary
MEIOSIS FERTILIZATION

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1.The Human Life Cycle
What is Sexual Reproduction?
 Read through the information and watch the video at
http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/genes/
 In the box below, type a definition of sexual reproduction.
 You must be is Slide Show to type and edit text in the box.
Sexual reproduction is the fusion of a haploid male and a
haploid female gamete which produces a diploid zygote
which grows into an offspring.CHECK

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1. Human Life Cycle
Mitosis
During our life cycle, two types of cell division occurs, and each has
specific functions. Mitosis, shown in the diagram, results in increase in
cells for growth, differentiation and repair of the body.

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1. Human Life Cycle
 When humans grow to adult stage, they are ready for sexual
reproduction.
 BUT …before sexual reproduction can occur, two things must
happen.What do you think they are? Type your answer in the box.
Feedback: If you said that a boy and girl must reach
puberty, they must begin to produce gametes as a
result of meiosis taking place in their reproductive
organs, you’d be quite correct!

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1. Human Life Cycle
The role of hormones at puberty
 In both sexes, hormones control the development of
secondarysecondary sexual characteristicssexual characteristics which marks the
onset of pubertypuberty and sexual maturitysexual maturity.
 These characteristics are the physical and emotional
attributes that clearly distinguish humans as masculine
or feminine and enable them to produce mature gametes

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1. Human Life Cycle
The role of the hormone estrogen
 You would remember that the ovaries are endocrine
glands.
 Under the influence of the pituitary gland and the
hypothalamus, ovaries produce oestrogens.
 Oestrogens control development of secondary sexual
characteristics in females.
 The diagram on the next slide will remind you of the
hormones that are involved.

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1. Human Life Cycle
The role of hormones
OvaryOvary
© Learning and Teaching Scotland 2011
HypothalamusHypothalamus
Follicle-stimulating
hormone
Lutenising hormone
Pituitary glandPituitary gland
Follicle matures Stimulates
ovulation
Oestrogens
Cause development of female sexual characteristics

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1. Human life Cycle
The role of testosterone
 You’ll no doubt also remember that the testes are
endocrine glands too.
 They produce the hormone testosterone.
 The testes also work under the influence of the pituitary
gland and the pituitary gland works under the influence
of the hypothalamus.
 Let’s review the function of the hormone testosterone.

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1. Human Life Cycle
The role of testosterone - Activity 1.1
 Testosterone - the ‘male hormone’ is responsible for
“maleness” in individuals.
 The testes are stimulated into action by Follicle
Stimulating Hormone produced by the pituitary gland.
This happens even before birth.
 As soon as a male reaches puberty he produces
testosterone in even larger quantities.
 Draw a flow chart similar to that done for the female
hormone oestrogens on slide 10, to show the control and
action of testosterone in males.
 Use the flow chart on the next slide to check your
diagram.

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1. Human Life Cycle
The role of testosterone - Feedback to Activity 1.1
HYPOTHALAMUSHYPOTHALAMUS
Follicle-stimulating hormone Lutenising hormone
Pituitary
gland
Pituitary
gland
Seminiferous tubulesSeminiferous tubules
TestesTestes
Interstitial cellsInterstitial cells
Testosterone stimulates development of male
sexual characteristics
Sperm production

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1. Human Life Cycle
DIDYOU KNOW?
 If a male’s pituitary gland is removed, he loses his male
characteristics.
 You should be able to figure out why that would happen.
Right?

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1. Human Life Cycle
Changes at Puberty - Activity 1.2
1. Look at the next slide.Think about what happened in
your own body or what you observed in females/males
in class/at home, then in your notebook or on the slide,
list the external secondary sexual changes that start at
puberty, in males and females, as shown by the arrows.
2. Then, think about the results of hormone activities and
also list internal secondary sexual changes in females
and males.

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1. Human Life Cycle
Changes at Puberty – Activity 1.2
1
2
3
4
6
7
9
5 8
1010
1111
CHECK
Look at the diagrams. Think about
what happened in your own body
or what you observed in
females/males in class/at home,
On the slide, list the external
secondary sexual changes that
start at puberty, in males and
females, as shown by the arrows.

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1. Human Life Cycle
Changes at Puberty – Feedback to Activity 1.2
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7
9
8
1010
Breasts enlarge, sometimes
at different rates, so one is
larger
Fat is deposited and the hips
broaden and curve much
more.
External genital organs and
internal reproductive organs
enlarge.
Menstrual cycle begins with
monthly ovulation.
Hair grows in the pubic area.
2
3
1
Hair grows
underarm.
4
Oil glands
become very
active leading to
possible
acne/pimples.
5
Development of facial
hair (e.g. beard)
Deepening of the voice
Broadening of the
shoulders
Development of chest and
pubic hair which has a
coarse texture.
The penis and testes grow
larger and the testes
begin to produce sperm.
Development of muscles
1111
MORE

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1. Human Life Cycle
Female secondary sexual characteristics
Here’s a summary of what you should have for changes in females:
1. Breasts enlarge, sometimes at different rates, so one is larger. .
2. Fat is deposited and the hips broaden and curve much more.
3. External genital organs and internal reproductive organs enlarge
and hair grows in the pubic area. Menstrual cycle begins with
monthly ovulation and a ‘period’ if there is no fertilization of the
egg and thus no pregnancy. Sexual desires start to develop.
4. Hair grows underarm. Increased sweating and body odours
become more noticeable.
5. Oil glands become very active leading to possible acne/pimples.
The teenage “growth spurt” occurs.
MORE

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1. Human Life Cycle
Male secondary sexual characteristics .
4.Development of axillary hair - hair grows underarm.There is increased sweating as
well as noticeable body odours.
5.Oil glands become very active leading to possible acne/pimples.
6.Development of facial hair (e.g. beard)
7.Deepening of the voice, which also ‘breaks’ as it varies between high and deep tones.
8.Broadening of the shoulders and development of muscles.
9.Development of chest and pubic hair which has a coarse texture.
10.The penis and testes grow larger and the testes begin to produce sperm. Sperm may
be ejaculated in semen, frequently occurring as ‘wet dreams’ (correctly called
nocturnal emissions). Sexual urges increase. Mood swings might occur.
The “growth spurt” begins and continues for a few years.
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1. Human Life Cycle
Changes at Puberty
 Boys – Take the time to read from the following website:
http://www.eschooltoday.com/boys-and-puberty/all-about-b
 Girls – Take the time to read from the following website:
http://eschooltoday.com/girls-and-puberty/all-about-girls-a
 Or find answers to some of your questions at
http://www.plannedparenthood.org/info-for-teens/our-bodi

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1. Human Life Cycle
Importance of secondary sexual characteristics
 Ovaries begin to mature an egg monthly.
 Enlarged vagina facilitates copulation during which sperm are deposited.
 The uterus can be prepared to accommodate the implantation of an embryo
if fertilization takes place.
 The vagina can act as the birth canal when necessary.
 Breasts enlarge to enable production of milk to feed the baby.
 Wider hips facilitate childbirth.
 The testes enlarge to facilitate sperm production that starts at puberty.
 The penis also enlarges to facilitate sexual intercourse during copulation in
which sperm are ejaculated into the female’s vagina.

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1. Human Life Cycle
Of course … all of theseOf course … all of these
characteristics definitelycharacteristics definitely
make males/femalesmake males/females
more attractive to themore attractive to the
opposite sex, thusopposite sex, thus
increasing the likelihoodincreasing the likelihood
of mating leading toof mating leading to
reproduction of thereproduction of the
species.species.

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1. Human Life Cycle
BUT … Think about this….
These characteristics will remain for a
very long time, so there’s no need to
rush to find a partner! Besides, all
men and all women have these
characteristics so you need to spend
time to know “what lies beneath the
surface” before you have sex!
Talk with a trusted relative, a 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 an STI such as HIV/AIDS.
Are you really
ready for that?
MORE
MORE

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2.The Significance of Meiosis
 When humans become sexually mature they can
produce gametes i.e. eggs and spermatozoa (sperm).
 Meiosis is the cell division through which eggs and
sperm are produced in their reproductive organs.
 Talk with your teacher about the diagram on the next
slide.
 Notice what happens to sections of chromosomes in
stage B, as that will influence the type of genetic
variation possible in offspring.

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Meiosis occurs in the ovaries/testes. During stage B, homologous
chromosomes that came from that person’s parents, swop sections
that each contain different alleles of various *genes.
*Genes are the
characteristics that
offspring inherit
from their parents
B

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Activity 2.1
1. Activity 2.1 consists of three questions related to the diagram on
slide 6.
2. On each question slide, type your answer in the box provided.You
must be in Slide Show view to type and edit text in the box.
3. Click the CHECK button for feedback.

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Activity 2.1 – Question 1
Question 1. When does meiosis start in the human life cycle? If you’re
not sure look at the life cycle diagram again. Type your response in
the box below. Click CHECK to see expected answer.
Meiosis starts when puberty begins.

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Question 2.What do you notice about the cells produced in meiosis,
shown at C? Type your response in the box below. Click CHECK to see
expected answer.
Each of the four haploid gametes (C ) resulting from one
cell (A) has half the number of chromosomes and a different
genetic makeup than the parent cell shown in (A).

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Question 3.What is the significance of Meiosis in the life cycle of
humans?
Meiosis is the cell division whose only purpose is to form male and
female gametes or sex cells that each contain the reduced or
haploid number of chromosomes. This reduction in chromosome
number is important so that when the two gametes fuse together
at fertilization, they form a zygote in which the correct or diploid
number of chromosomes is restored in the offspring that will
develop from the zygote.

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Challenge!
If you’re interested in the details of meiosisdetails of meiosis --- just click, watch/ read
from
http://www.sumanasinc.com/webcontent/animations/content/meiosis.html
Key Points of Meiosis
•The process results in 4 daughter cells
•Daughter cells are haploid (N)
•Daughter cells have unique combinations of
chromosomes .
•Daughter cells do not have homologous pairs .
•Meiosis creates gametes (sperm and eggs).
•Meiosis ensures variability in offspring.
Key Points of Meiosis
•The process results in 4 daughter cells
•Daughter cells are haploid (N)
•Daughter cells have unique combinations of
chromosomes .
•Daughter cells do not have homologous pairs .
•Meiosis creates gametes (sperm and eggs).
•Meiosis ensures variability in offspring.

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Significance of Meiosis cont.
 If gametes are not haploid, there can be several
anomalies.
 For example: If something goes wrong during meiosis
and the chromosome reduction fails to occur, then the
offspring ends up with an extra 21st chromosome, s/he
can have Down’s syndrome.
 Look at the photos on the next slide.

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Significance of Meiosis
These photos show children who
have Down’s snydrome
Persons with Down’s syndrome
have:
Almond shaped eyes
Short neck
Enlarged tongue
Congenital heart defects
Flat nasal bridge

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2. Significance of Meiosis
Klinefelter’s syndrome
 Here’s another example - If a person has an extra X
chromosome, s/he can have Klinefelter’s syndrome
 Click to the website and look at the illustration of a
person with Klinefelter’s syndrome
http://www.beliefnet.com/healthandhealing/images/si555

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Turner’s Syndrome
Turner’s syndrome can
result if there is one less X
chromosome in females.
Photo of child with
syndrome 

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Turner’s Syndrome
A person with Turner’s syndrome has:
 small stature
 a broad chest and small breasts
 webbed neck
 puffiness of hands and feet
 are infertile
Look at some of the photos that show people who have
Turner’s syndrome, at>
http://turnersyndromepictures.net/Turner-S-Syndrome-
Facts.php

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3. The male reproductive system in humans
Activity 3.1
1. The diagrams at the following website illustrate the
male reproductive system.
http://www.xtec.cat/~dfarre1/projecte/reproduction.htm
An accessory gland is labeled on the diagram. It is the
bulbourethral gland or Cowper’s gland. Find out its
function by reading the text at that web-link above.
Then also read and watch the video at >
http://www.medicalook.com/human_anatomy/systems/Male_Reprod
uctive_System.html

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3.The male reproductive system
Activity 3.1 cont.
2. You’ve now recalled the parts of the male reproductive
system. Click link to the website below.Then, here’s
the challenge. See if you can correctly identify the
numbered parts on the two sides of the first and second
models at:
http://legacy.bluegrass.kctcs.edu/natural_sciences/biology/bio_139_virt
ual_lab/virtual_lab_10/male_reproductive_model/malefulltorsolabeled/
3. Now look at the third and fourth sectional models… can
you identify reproductive structures? Name them for
your teacher.
4. Click where it says to check your answers.

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3. The male reproductive system
Sperm
 The male organs of the reproductive system are structured to
produce, temporarily store and periodically release spermatozoa.
The spermatozoa are mixed with nourishing fluids and together they
are called semen.
 The release of semen is called ejaculation.
 In humans, maleness comes from having both X andY
chromosomes, that make up the 23 pairs (=46). Females have XX.
 Because of meiosis, each sperm has either an X or a Y chromosome
and also contains the haploid number (23) chromosomes.
 So, the Y chromosome determines maleness.

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3. The male reproductive system
The male gamete or spermatozoon (sperm)
Look at the parts of
a sperm or
spermatozoon.
The three parts are:
the head (it contains
the nucleus) the
middle-piece (has
mitochondria) and
the tail which
enables it to move.

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4.The female reproductive system
 The diagrams in the following slides illustrate the female
reproductive system.
 Pay close attention as your teacher guides you through
the diagrams.
 Unlike the male system, most of the parts are internal.
 Note that there are separate passages for the urethra,
anus and the vagina.

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Location and parts

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Location and External Parts
 Click open the following link, scroll down to ‘The
Female Reproductive System’ and examine the first and
second set of diagrams:
http://ridge.icu.ac.jp/biobk/BioBookREPROD.html
 If you’ve fully understood the parts of the female
reproductive system, then you should have no problem
at all identifying the parts on these models at the website
below.
 Give it a try! Click open:
http://legacy.bluegrass.kctcs.edu/natural_sciences/biology/bio_139_
virtual_lab/virtual_lab_10/female_reproductive_model/

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Activity 4.1:Write a blog
 Reflect on all that you’ve learned about cell division and
the human reproductive systems.
 Was there anything that surprised you?
 What new information did you gain?
 Write a brief blog about it and get help from your
Science or IT teacher to find out how you can post your
blog on line. If you do not have a blog, type your
responses to the questions in the box on the next slide.
 Think about it … if it is new to you, or if there were
something that surprised you, it might also be new or
surprising to others your age!

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Activity 4.1:Write a blogActivity 4.1:Write a blog
 Reflect on all that you’ve learned about cell division and
the human reproductive systems.
 Was there anything that surprised you?
 What new information did you gain?
 Share your blog with your teacher and classmates.

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Career Focus
 A gynaecologist is a medical practitioner who deals with the health
of the female reproductive system, i.e., the vagina, uterus and
oviducts and the ovaries.
 S/he deals with such problems as cancer, endometriosis, fibroids,
absence of or painful menstrual periods, infections, infertility and
hysterectomies and will also perform tubal ligations.
 Are you interested in such a career?
 If so, you should find out what qualifications you need to gain entry
into a training programme at The UWI or overseas.

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SUMMARY
Click and read from:
 http://ubykotex.co.nz/puberty/male/reproductive-
system/
 http://ubykotex.co.nz/puberty/female/

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QUICK QUIZ – Part 1QUICK QUIZ – Part 1
Click open and do each Quiz. Check your answer AFTER you’ve
completed each Quiz
Start with this quiz of 8 M.C items.
http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Qui
z_Male_reproductive_system
Do ‘Labelling exercise 27.4’ at:
http://www.mhhe.com/biosci/ap/saladin2e/graphics/saladin02ap/ch
27/others/chap27labeling04.html
Do ‘Labelling exercise 27.5 at:
Do ‘Labelling exercise 27.10 at:
47

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QUICK QUIZ – Part 2
Label the diagram below and write annotations for each label.
CHECK

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Feedback to QUICK QUIZ Part 2
Label the diagram below and write annotations for each label.

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QUICK QUIZ – Part 3 TEST YOURSELF!
 Click open this website and scroll down to the heading ‘Health
-Sexuality’ http://thornlea.sharpschool.com/cms/One.aspx?
portalId=119587&pageId=781290
 Work with a partner and take turns testing each other.
 There are nine tests there that both of you can try. Start from the first
test titled ‘Puberty in Females’ and go right down to ‘The Female
Reproductive System’, just above the ‘Menstrual Cycle 1’ test.
 If either you or your partner are uncertain of an answer, check in
your SIM or at the website in the Summary of this slide set, or ask
your teacher for help.

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End of Activity
 You have reached the end of this Power point slide
presentation.
 If you wish to review any of the concepts in this lesson,
go to the first slide and click on the subtopic.
 If you have finished viewing the lesson, click the Close
(X) button.
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