The Reproductive System

What do I need to know? The structure and function of the parts of the male and female reproductive system The Menstrual Cycle Sexual Intercourse Fertilisation Pregnancy Birth – including growth of the baby Contraception Methods

The male reproductive system The male reproduction system produces and delivers the male gamete (sperm) Seminal Vesicle Sperm Duct Side view

The Male Reproductive System Testis The testis (Testes) makes sperm They start to make sperm between the ages of 12 and 14 – Puberty Sperm are the male sex cells (also called gametes) Each sperm cell is tiny and they are produced in large numbers by the testes.

Scrotum The scrotum is a sac in which the testes are held The scrotum allows the testes to be kept at a temperature just below body temperature – this allows sperms to be made successfully

Sperm Ducts Two sperm ducts carry sperm from the testes to the penis A number of glands are located beside the sperm ducts These glands produce a liquid called seminal fluid in which sperm are released The combination of sperm and seminal fluid is called semen

Penis The sperm ducts join to form a tube called the urethra Sperm pass through this tube, which is located in the centre of the penis The penis allows semen (or sperm) to pass out of the male body and into the body of the female

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

Ovary The ovaries produce eggs The ovaries start to make eggs at puberty Eggs are the female sex cells or gametes Each egg is larger than a sperm cell Normally one egg is formed each month in the female body from puberty until about 50 years of age At this stage, called the Menopause, the female stops forming eggs

Fallopian Tube & Uterus The fallopian tube collects the egg from the ovary and carries it to the uterus If sperm are present one of them may join with the egg in the fallopian tube. If there are no sperm present the egg dies UTERUS The uterus or womb is the area in which a baby (or embryo) will develop

Cervix & Vagina The cervix is the opening or the neck of the uterus Sperm pass through the cervix in order to reach an egg Vagina The vagina is a muscular tube into which the penis releases sperm It forms the birth canal when the baby passes down the vagina at childbirth

The menstrual cycle 28 day cycle in the female link to animation 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

Stages in the menstrual cycle 28 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

Days 1 - 5 The lining of the uterus (which had built up during the previous menstrual cycle) breaks down. This lining along with some blood, is passed out of the body through the vagina This process is called menstruation or having a period During these days an egg matures in the ovary

Days 6 - 13 A new lining develops in the uterus The lining will be needed to nourish a developing baby if the female becomes pregnant The egg continues to develop in the ovary

Day 14 The egg is released from the ovary This is called ovulation The egg can survive for two days in the fallopian tube Ovulation is the release of an egg from the ovary

Day 15 - 28 The lining of the uterus remains in place until it breaks down on the first day of the next menstrual cycle

The Fertile Period The fertile period is the days in the menstrual cycle when a female is most likely to become pregnant if she has intercourse Sperm can stay alive in the female reproductive system for up to three days - this means that pregnancy can occur if the female has intercourse 3 days before ovulation The egg can stay alive for 2 days after ovulation – this means that pregnancy can occur if the female has intercourse 2 days after ovulation

This means that the fertile period lasts from day 11 to day 16 in a typical menstrual cycle Menstrual cycles can be longer or shorter in different females – the fertile period is different for every female In some cycles the fertile period could start as early as day 8 or 9, while in other cycles it could last until day 18 or beyond

Sexual intercourse The 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

Fertilisation Occurs when a male gamete (sperm) fuses with the female gamete (egg) to form a zygote Also referred to as conception SPERM +EGG = ZYGOTE Sperm + egg = zygote

Path of the Sperm Normally over 100 million sperm are released into the vagina The sperm swim through the cervix and into the uterus They can swim from the uterus towards the fallopian tube If there is no egg present in the fallopian tube the sperm die within three days

Fertilisation Fertilisation usually happens in the oviduct / fallopian tube A fertilised egg – zygote - may then move down into the wall of the uterus / womb

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

Birth After about 40 weeks, when the baby is fully developed, the following happens: The sac of protective fluid breaks open The muscles of the uterus / womb contract very strongly to push the baby out After the baby is born, the placenta is also pushed out of the womb The umbilical cord between baby and placenta is cut

Contraception Main methods of preventing conception: Chemical - prevention of gamete formation e.g. the Pill Physical barrier – preventing the gametes from meeting e.g. condom Timing – avoiding sexual intercourse during the fertile period of the menstrual cycle