1. Mrs Theresa Teo/2003 1 Sexual Reproduction in Animals Lesson 2 : Human Reproduction (cont’d)

2. Mrs Theresa Teo/2003 2 We went through –the need for reproduction. –the male and female gametes in animals. –internal and external fertilisation –development of eggs internally and externally –the place where male and female gametes are produced or stored in human beings. REVISION OF PREVIOUS LESSON

3. Mrs Theresa Teo/2003 3 Discuss in your groups : 1.Would you like to have children? 2.How many children would you like? 3.At what age would you start considering getting married? 4.Should people get married before they have children? Why? Let’s share our views about having children – Activity 1

4. Mrs Theresa Teo/2003 4 By the end of the lesson, you should have an understanding of how human beings are reproduced or how children are produced. Let’s look at the parts of the male and female reproductive system again. TODAY’S LESSON

5. Mrs Theresa Teo/2003 5 Reproductive system - Male epididymis / Cowper’s gland

6. Mrs Theresa Teo/2003 6 Reproductive system – Female

7. Mrs Theresa Teo/2003 7 We know that the male gamete is found in the testes and the female gamete is found in the ovaries. The question is how do we get the sperm and the egg to fuse together so that the egg can be fertilised and what happens after the egg is fertilised in human beings (in mammals). This cannot happen at any age. It can only start happening after the human being matures or reaches puberty. Physical maturity is one thing. Mental maturity is another. What do you think? TODAY’S LESSON

8. Mrs Theresa Teo/2003 8 Puberty (Physical maturity) The age at which secondary sexual characteristics appear and gametes (sex cells) begin to be produced or released Some general changes in both girls and boys. Height increases Face changes Armpit hair and pubic hair start to grow Sex organ develops and is capable of releasing the sex cells.

9. Mrs Theresa Teo/2003 9 Sex Cells Male Sex Cells –Called sperms –Produced by testes –Produced until old age –Capable of moving on their own –Millions of sperms released during each ejaculation Female Sex Cells –Called eggs/ova –Produced by ovaries –Produced until menopause –Not capable of moving themselves –Only one is released during ovulation

10. Mrs Theresa Teo/2003 10 Human Sperm Contains mitochondria which provides energy for the sperm’s activity Enables the sperm to swim towards egg

11. Mrs Theresa Teo/2003 11 Human Egg

12. Mrs Theresa Teo/2003 12 Puberty Specific changes in the male  Boys usually reach puberty at an average age of 13 years.  Sex organ starts to produce sperms  Shoulder and chest become broader  Voice breaks and deepens  Moustache and beard start to grow

13. Mrs Theresa Teo/2003 13 Puberty  Specific changes in the female  When a baby girl is born, the ovaries already contain around 400 000 ova or eggs.  Girls tend to mature two years earlier than boys (average age of 11)  When she matures, a small fraction of these eggs mature (approx. 450) and is released from alternate ovaries each month.  Breasts develop  Hips widen  Undergoes the menstrual cycle

14. Mrs Theresa Teo/2003 14 MENSTRUAL CYCLE 1.It is a cycle that mature girls go through. 2.It is the sequence of changes which occurs in the wall of the uterus in the course of 28 days (approx. once every month) 3.The changes are controlled by hormones secreted by the ovary. 4.3 main events occur in the cycle. a.The lining of the uterus wall thickens to prepare for the coming of the embryo. b.Ovulation – the release of ovum from the ovary once every month c.Menstruation – lining of uterus wall breaks down and flows out of the vagina as blood. –Menstruation happens only if the ovum (i.e the egg) does not get fertilised by a sperm.

15. Mrs Theresa Teo/2003 15 Menstrual Cycle

16. Mrs Theresa Teo/2003 16 What if fertilisation does occur? HOW DOES FERTILISATION OCCUR? 1.There is mating. 2.Sperms are introduced into the female through the vagina. 3.The sperms swim through the uterus to the oviduct towards the egg. 4.A sperm bumps into the egg. 5.The sperm penetrates the egg membrane. 6.The tail drops. 7.The egg membrane thickens to prevent other sperms from entering. 8.The sperm nucleus fuses with the egg nucleus.

17. Mrs Theresa Teo/2003 17 Fertilisation

18. Mrs Theresa Teo/2003 18 Fertilisation

19. Mrs Theresa Teo/2003 19 What happens after fertilisation? 1.The egg is now a zygote. 2.The zygote divides into hundreds of cells to become an embryo as it passes further down the Fallopian tube or oviduct on the way to the uterus. 3.The embryo then becomes embedded in the uterine wall which is now thick and rich in blood vessels. This is called implantation. 4.This embryo continues to divide and the blood, blood vessels and heart are among the first features to develop. 5.A fluid-filled sac called the amniotic sac protects the embryo. 6.The embryo gets nutrients, oxygen and antibodies from the blood vessels in the lining of the uterus called the placenta.

20. Mrs Theresa Teo/2003 20 What happens after fertilisation? 7.The embryo passes the urea and carbon dioxide back to the mother. 8.The embryo is attached to the placenta by the umbilical cord. 9.Eventually, the cells develop into different types of tissues and organs. 10.When all the main parts of the body and the internal organs are formed, it is called a foetus. 11.Growth and development continues till around the 40 th week when the muscles of the uterus start to contract and the process of giving birth begins. 12.The amniotic sac breaks and the contractions increase in intensity and frequency, and the baby is pushed through the vagina and out of the female’s body.

21. Mrs Theresa Teo/2003 21 Foetus Development 5 months9 months

22. Mrs Theresa Teo/2003 22 Fetus Development and Structure

23. Mrs Theresa Teo/2003 23 Birth of baby

24. Mrs Theresa Teo/2003 24 For you to ponder about physical maturity vs mental maturity Is mental maturity (i.e. are you ready to have children mentally) important? What do you mean by being mentally ready? What must you get ready before children come along? JOT DOWN YOUR THOUGHTS ON YOUR WORKSHEET. I’M INTERESTED TO KNOW.