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1B4 Human Reproduction

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OB31 use wall charts or other illustrative diagrams to identify and locate the main parts of the male and female reproductive systems

OB32 recall that the menstrual cycle lasts about 28 days and that menstruation occurs at the start of the cycle

OB33 understand the following in relation tohuman reproduction:• fertile period in the menstrual cycle• sexual intercourse• fertilisation is the fusion between male and female gametes (sperm and egg) resulting in a zygote; a zygote undergoes cell division and develops within the womb into a foetus • pregnancy and birth• growth and puberty

OB34 understand that there are many forms of contraception, and that some of these prevent fertilisation

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The male reproductive system

The male reproduction system produces and delivers the male gamete (sperm) link to interactive diagram at

Kid’sHealth

Seminal Vesicle

Sperm Duct

Side view

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The female reproductive system

The female reproduction system produces the female gamete (egg) and protects the developing embryo / foetus

link to interactive diagram at Kid’sHealth

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Growth & Puberty

• Growth is a characteristic of all living things

• During puberty the reproductive systems mature

• After puberty a human is called an adult

link to animation at bbc.co.uk

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The menstrual cycle

• 28 day cycle in the female

• Controlled by chemicals called hormones

• An egg is produced, and the womb develops a thick lining of blood vessels to be prepared for pregnancy

• If the egg is not fertilised, the lining leaves the womb – menstruation – and the cycle begins again

link to animation

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Stages in the menstrual cycle28 day cycle

Approx. days

1 - 5 Menstruation – loss of uterus lining and unfertilised egg

5 - 13 Repair of uterus lining

14 Release of egg from ovary

14 - 28 Build up of lining of uterus

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Fertile period in the menstrual cycle

The egg is, usually, released around

Day 14 of a 28 day cycle

Fertilisation is possible for several days around this time

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Sexual intercourseThe natural process of

transferring the sperm from the body of a male to the body of a female

Millions of sperm are transferred in a fluid called semen…they immediately begin swimming towards the single egg cell

link to ‘how stuff works’ animation

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• Occurs when a male gamete (sperm) fuses with the female gamete (egg) to form a zygote

• Also referred to as conception

Sperm + egg = zygote

Fertilisation

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• Fertilisation usually happens in the oviduct / fallopian tube

• A fertilised egg – zygote - may then move down into the wall of the uterus / womb

Fertilisation

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Pregnancy• a zygote undergoes

cell division and develops within the womb into a foetus

• over 40 weeks the foetus develops all its human features

• It develops inside a protective sac of fluid

• It receives food via a blood supply in the placenta

link to animation

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BirthAfter about 40 weeks, when the baby is fully developed, the following happens:

1. The sac of protective fluid breaks open

2. The muscles of the uterus / womb contract very strongly to push the baby out

3. After the baby is born, the placenta is also pushed out of the womb

4. The umbilical cord between baby and placenta is cut

Links to an animation – may be slow to load…

Link to birth animation

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Contraception

Main methods of preventing conception:

1. Chemical - prevention of gamete formation e.g. the Pill

2. Physical barrier – preventing the gametes from meeting e.g. condom

3. Timing – avoiding sexual intercourse during the fertile period of the menstrual cycle

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Find the answers:

• Why are human babies born so “helpless” compared to some animal babies?

• Why are human babies’ heads so big in comparison to their bodies?

• What are conjoined twins and how do they occur?

• What is foetal alcohol syndrome ?

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1B4 Human Reproduction