Chapter overview

2 weeks

After looking at several of the organ systems within the human body in overview in Chapter 2, the next three chapters will now look at some of these systems in more detail.

This chapter on "Human reproduction" starts off by looking at the purpose of reproduction and how humans mature during puberty in order to be able to reproduce. This will be very relevant to your learners as they are in this stage in their lives at the moment.

Be aware that learners might not feel comfortable discussing reproduction in the classroom, and older teens might laugh or make inappropriate jokes to conceal their own discomfort.

Some tips for when teaching human reproduction:

3.1 Purpose and puberty (2 hours)

Tasks

Skills

Recommendation

Activity: Reflecting on population growth

Identifying, predicting, writing

Optional

3.2 Reproductive organs (1 hour)

Tasks

Skills

Recommendation

Activity: Identify the role of the male and female bodies in reproduction

Identifying, writing

Suggested

Activity: Identify structure and function

Identifying, describing, explaining, writing

CAPS suggested

Activity: Comparing the reproductive organs

Comparing, summarising, writing

Suggested

3.3 Stages of reproduction (3 hours)

Tasks

Skills

Recommendation

Activity: Flow diagram of the pathway of sperm

Summarising, describing

CAPS suggested

Activity: Comparing fertilisation and menstruation

Comparing, summarising, drawing

Suggested

Activity: Debate Surrogacy

Working in groups, discussing, debating, presenting, writing

CAPS suggested

Activity: Describing different contraceptives

Identifying, describing

Optional

Activity: Forum discussion

Working in groups, discussing, debating, presenting, writing

Optional

At this stage in your life, your body is probably going through all sorts of changes as it grows, develops and matures. In this chapter we will learn more about these changes and why they occur.

You have previously learnt that reproduction is one of the seven life processes, and like all organisms, humans need to reproduce to ensure the survival of the species.

You can use this section to open up discussion about population growth and population control. At the end of the chapter there is a debate regarding contraceptives but teachers may choose to include a discussion on the different ethical points of view regarding contraceptives at this point already.

Video on our world population growth.

An interesting suggestion if you have an internet connection and a projector or smartboard to display a website, is to open up the link provided here in the visit box on our "Breathing Earth". This simulation very clearly shows how our population is growing. You can open up the link at the start of the lesson and leave it running for the duration. Then at the end of the lesson, you can see how much the population of the world has grown during your one lesson. Alternatively, if you do not have an internet connection in your classroom, ask some of your learners to take out their mobile phones and go to the site. Even if you only have a few mobile phones within the classroom, you can get learners to each take a look at the site at the start and end of the lesson. Do not be afraid to embrace the technology that your learners are using on a daily basis! They most likely have their cellphones in their pockets in class anyway, unless they have been banned during school hours.

Have a look at the website link provided in the visit box about our "Breathing Earth". This will give you an idea about how our population is growing.

In 2011 the world's population grew to 7 billion people, one billion more since 1999. Medical advances and increases in agricultural production (food) allow more and more people to live longer lives.

In ancient times, countries such as India, Rome and Greece, saw a large population as a source of power. The Romans even made laws about how many babies a couple could have and punished those who did not follow the rules. Yet Confucius (551-478 BC) thought that too many people was a problem, as there wouldn't be enough food to feed everyone, leading to war and famine and various other problems. Today in China this philosophy still applies and couples are only allowed one baby and are heavily taxed if they have more than one.

South Africa's population grew by 15,5%, or almost 7-million people, in the space of 10 years to reach a total of 51.7-million in 2011. This is according to the country's latest national census which took place in 2011. The last census took place 10 years previously in 2001.

QUESTIONS:

These questions are meant to stimulate discussion within your class. You can go through these as a class or learners can then do them individually and then discuss their answers.

List any possible reasons why you think South Africa would want to have a large population.

Learner-dependent answer. Might include: more people so more manpower and more taxes; might include religious or cultural bias; etc.

What are some advantages and disadvantages to the country in which the number of children per couple is limited so that the population growth is limited?

Advantages: lower population growth; lower pressure on the country's resources; lower drain on resources, particularly on the education resources; higher standard of living for families

Disadvantages: fewer people to pay taxes; religious or cultural non-compliance might lead to revolt

Predict what possible long-term problems might arise if the population in South Africa continues to grow at the fast rate at which it is currently growing.

With fewer resources to go around many might starve and since they might not have work or social grants to support them. Unemployment would increase even more. This might also lead to increased crime as people try to provide for themselves and their children, as well as drug and alcohol abuse as a coping mechanism.

Have a look at the following diagram which shows the percentage growth a country's population in a year. The different colours give an indication of the growth rate, as shown in the key. For example, countries which are colour coded yellow, have an annual growth rate of 3%. This means their population increase by 3% each year. Answer the questions which follow.

Which continent would you say has the largest percentage growth rate each year? Justify your answer.

Africa has the largest population growth rate. This can be seen as it has the largest number of countries which are coloured green and yellow which shows the highest annual percentage growth rate.

Many countries in Europe are coloured light purple in the diagram. What does this mean?

Learners need to look at the legend to see that light purple means a growth rate of "

Various population control methods are put in place around the world - contraceptives to stop women from falling pregnant, abortion clinics, large tax incentives to convince people not to want more children, and others. What is your opinion about population control methods and do you think they should be allowed in modern society?

Learner-dependent answer.

The science of overpopulation (video).

The human body is geared towards reproduction to ensure the survival of the species. Men have to produce sperm and ensure that they come into contact with a female egg cell. Women have to produce (and store) egg cells that can be fertilised by a male sperm cell.

Children's bodies and sexual organs are not mature and cannot yet perform the reproductive function. Puberty is therefore the time when a child's body develops and changes. The sexual organs mature to enable the body to produce sex cells. These sex cells are called gametes.

Puberty is the stage in the life cycle of humans when we become capable of sexual reproduction. Girls and boys do not, generally, go through puberty at exactly the same time. So how does puberty "start"?

Many of the complex actions that take place in our bodies are controlled by chemical messengers called hormones. Hormones are produced by different glands in our bodies. The pituitary gland is an important gland which controls most of the body's hormones and hormonal activities. It is about the size of a pea and located at the base of the brain.

Puberty is brought on when the pituitary gland releases specific hormones into the bloodstream. These hormones then travel to the immature sex organs and signal the hormones in these to be released.

In girls, the ovaries are stimulated by hormones released by the pituitary gland to release the hormone oestrogen. In males, the testes are stimulated to release the hormone testosterone. These hormones initiate all the bodily changes that you experience during puberty.

The main purpose of puberty is for the sexual organs to mature. However, the hormones which are released from the reproductive organs also start a number of other changes in the human body. We call these secondary sexual characteristics.

Puberty brings about the following secondary changes in females:

At the start of puberty boys are, on average, 2 cm shorter than girls, yet adult men are approximately 13 cm taller than adult women. Puberty brings about the following secondary changes in males' bodies:

Let's take a look at the reproductive organs.

Let's take a closer look at the male and female reproductive organs to see how they are structured and what functions they perform.

In the space below, explain what you think the role of the male and female bodies are in reproduction.

The male body has to produce sperm and deliver this sperm to the female body in order for it to come into contact with the female egg (ovum).

The female body has to...

The female body has to produce ova (egg cells). Once a month, one egg cell is released and if a sperm cell penetrates the outer layer of the egg cell, fertilisation can take place. This may then lead to pregnancy and the female body adapts to provide for all the needs of the unborn baby before giving birth.

As you learn about the reproductive organs,think carefully about theirstructure and how their structure is adapted to their function.

The male reproductive organs include:

1. Testes and scrotum

Males are born with their two testes hanging outside their bodies. The testes in young boys do not produce sperm. During puberty the two testes release testosterone which then triggers the production of sperm.

Testes is plural and testis is singular.

Up until the 17th century, scientists believed that a tiny, fully formed human being called ahomunculus was passed from the father into the mother's womb during sexual intercourse and grew in size in the mother's womb.

The two testes are each contained in a pouch of skin called the scrotum. The scrotum ensures that the testes are kept at a constant temperature of 35C which is the temperature at which sperm is produced.

Semen contains sperm cells, dissolved nutrients and enzymes that nourish and protect the sperm inside the woman's body. Every millilitre of semen can contain up to 100 million sperm cells!

2. Sperm duct (vas deferens)

Different tubes (ducts) carry the semen from the testes to the penis. The sperm duct carries the sperm from the testes to the urethra in the penis.

3. The penis

The penis is the external sex organ. The head is often covered by a loose fold of skin called the foreskin. The penis needs to be erect (stiff and hard) to be able to go into the vagina to deliver the sperm to the cervix during ejaculation.

Some cultures have the foreskin removed, which is called circumcision. This may be done when the boy is a baby or later, at puberty.

4. Urethra

Originally posted here:
Stages Of Reproduction | Human Reproduction | Siyavula