The Reproductive System Chapter 10 Exploring Science 3rd Edition Ms. O’Rourke

Recap Fertilisation

Human Reproduction Humans reproduce sexually. Involving two parents one female and one male.

link to ‘how stuff works’ animation Sexual intercourse Sexual intercourse (copulation) take place and semen to be released from the penis. link to ‘how stuff works’ animation

Millions of sperm are released into the vagina. The sperm swim through the cervix and into the uterus. They swim from the uterus towards a fallopian tube.

Fertilisation takes place when the nucleus of a sperm joins or fuses with the nucleus of an egg. This takes place in the fallopian tube The fertilised egg forms a single cell called a zygote. Fertilisation the joining of the nucleus of a sperm with the nucleus of an egg.

Fertilisation video http://www.youtube.com/watch?v=-56ZrHcVCQQ

Fertilisation 8 8

Fertilisation Fertilisation usually occurs in the fallopian tube A fertilised egg then moves down into the wall of the uterus / womb 9 9

Fertilisation in the fallopian tube. 10 10

Pregnancy Once the zygote has formed it goes through many cell divisions to form a ball of cells. Theses cells then form an embryo. The embryo becomes attached to the lining of the uterus. This attachment is called Implantation.

Implantation The attachment of the embryo to the lining of the uterus. This occurs 6-9 days after fertilisation

Zygote Implanted embryo Implantation is the embedding of the fertilised egg into the lining of the uterus 13 13

Pregnancy The embryo becomes surrounded by a membrane called the amnion. This membrane fills up with a liquid called amniotic fluid. Amniotic fluid acts as a shock absorber

Pregnancy After 8 weeks, the embryo can be recognised as a human. At this stage, it is called a foetus. Pregnancy normally lasts from implantation until birth. A normal pregnancy lasts around 40 weeks (about 9 months).

Pregnancy Carrying an embryo (or offspring) in the uterus.

The Placenta The placenta’s function is to allow materials to pass between the mother and the baby in the uterus.

The Placenta A structure called the placenta forms early in pregnancy. The baby’s blood passes through the umbilical cord to and from the placenta.

Placenta

The placenta forms from a combination of the tissues of the uterus and the embryo. Development & function of the placenta

The Placenta Chorion Embryo Placenta Mother’s blood Amnion Nutrients, Oxygen, antibodies Wastes, Carbon Dioxide, Water Amnion Amniotic fluid Umbilical cord Embryo’s blood Embryo 22 22

The Placenta The blood of the mother and embryo do not mix. This is important as: The blood groups of the mother and baby might not be compatible.

Baby Formation Four to five weeks after fertilisation The heart forms and starts to beat. The brain also develops. The limbs have started to form.

Baby at 5 weeks

By the 6th week Eyes are visible The mouth, nose, and ears are forming. The skeleton is at the early stage of development.

By the 8th week The major body organs are formed Sex glands have developed into testes or ovaries. Bone is beginning to replace cartilage.

At this stage the embryo has taken on a recognisably human form. From this point it is referred to as a foetus. The foetus continues to grow. No new organs are formed from this point.

By the 12th week (3 months) The nerves and muscle become coordinated allowing the arms and legs to move. The foetus sucks its thumb, urinates and even releases faeces into the amniotic fluid. The gender of the foetus can be seen in scans.

Baby development http://www.youtube.com/watch?v=lw0M-HTlMoo&feature=share&list=PL9FE21D2472A12B0E

Birth

Birth Towards the end of pregnancy, muscles in the uterus begin to contract these contractions are called labour. These contractions cause the amnion to burst. The release of liquid through the vagina is called the ‘breaking of the waters’.

The cervix gradually widens during these contractions. The contractions cause the baby to be pushed head first out through the cervix and the vagina. The umbilical cord is clamped (to prevent loss of blood from the baby) and cut. The baby soon starts to breathe through its lungs for the first time.

The uterus continues to contract after the baby is born The uterus continues to contract after the baby is born. These contractions push the placenta and the remains of the umbilical cord out of the vagina. These materials are called the afterbirth.

Birth

3 stages in birth Stage 1 (about 12 hours) The contractions of the uterus pushes the foetus towards the cervix. This cause the cervix to open (dilate). During this stage the contractions cause the amnion to break releasing the amniotic fluid through the vagina.

There are three main stages: Stage 1 - (about 12hrs) The contraction of the uterus pushes the foetus towards the cervix. This causes the cervix to open (dilate). During this stage the contractions cause the amnion to break releasing the amniotic fluid through the vagina. (The ‘waters break’). 40 40

Stage 2 - (20 minutes to 1 hour) The foetus passes through the cervix and the birth canal head first. 41 41

Stage 2 - (20 minutes to 1 hour) The foetus passes through the cervix and the birth canal head first. 42 42

Stage 2 - (20 minutes to 1 hour) The foetus passes through the cervix and the birth canal head first. 43 43

Stage 2 - (20 minutes to 1 hour) The foetus passes through the cervix and the birth canal head first. 44 44

Stage 2 - (20 minutes to 1 hour) The foetus passes through the cervix and the birth canal head first. 45 45

Stage 2 - (20 minutes to 1 hour) The foetus passes through the cervix and the birth canal head first. The umbilical cord is tied and cut. This leaves a scar which will eventually become the navel (belly button). 46 46

Stage 3 - (10 to 15 minutes) The baby is now born. The uterus now contracts again and expels the afterbirth - the umbilical cord and placenta. 47 47

Stage 3 - (10 to 15 minutes) The baby is now born. The uterus now contracts again and expels the afterbirth (the umbilical cord and placenta. 48 48

Stage 3 - (10 to 15 minutes) The baby is now born. The uterus now contracts again and expels the afterbirth (the umbilical cord and placenta. 49 49

Stages of birth

Umbilical cord is cut 51 51

Growth of the baby The baby may feed on breast milk produced by the mother. This milk is full of the ideal nutrients that a young baby needs. It contains many antibodies (substances) which help to protect the baby from infections. The remains of the umbilical cord falls away from the baby’s navel after about 7 days.

Breastfeeding Breastfeeding is better than bottle feeding because: Colostrum and breast milk provides the baby with essential antibodies protecting it against infection. Ideal balance of nutrients for the baby Has little fat making it easier to digest than milk.

Contraception Contraception is the prevention of fertilisation or pregnancy. Some couples want to control the number of children they have or to control how soon after each other their children are born. 54

Others wish to have sexual intercourse without the female becoming pregnant. These people may use contraception as a method of birth control, family planning, in order to prevent unwanted pregnancies. There are two main types of contraception: Preventing fertilisation and preventing implantation.

Contraception 14. 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 56

Removing the possibility of conception is called contraception. Birth control Birth control refers to the methods employed to limit the number of children that are born Removing the possibility of conception is called contraception. This is achieved by preventing the egg and sperm from meeting. 57 57

Mechanical contraception - male The use of condoms Surgical contraception -Sperm ducts are cut and tied 58 58

Mechanical contraception - Female The use of diaphragms - a cervical barrier type of birth control. It is a soft latex or silicone dome with a spring molded into the rim. The spring creates a seal against the walls of the vagina. 59 59

Chemical contraception - The Pill There are two types of oral contraceptive pill. The combined oral contraceptive pill: more widely used, taken for 21 days and contains a combination of two hormones, oestrogen and a progestogen. Affects the production of FSH and LH. Ovulation is interrupted, the ovary does not release an egg and pregnancy cannot occur. Taken correctly, the combined pill is a very reliable contraceptive with a failure rate of less than one pregnancy per 100 woman-years. This means that less than one pregnancy will occur among 100 women using this method for a year. However, this presumes that the pill is taken correctly. If the pill is forgotten then the woman is not adequately protected and could become pregnant. In actual use, the failure rate is likely to be between two and three pregnancies per 100 woman-years. 60 60

2. The minipill or progestogen-only pill: works mainly by changing the chemical composition of the mucus in the cervix (neck of the womb) making it impenetrable to sperm. In some women it may prevent ovulation but this effect is variable. The minipill is taken continuously for 28 days without a break. The minipill is slightly less effective than the combined pill. In ideal use, it has a failure rate of less than two pregnancies per 100 woman-years. This means that fewer than two pregnancies will occur among 100 women using this method for a year. 61 61

Spermicide Spermicides come in several different forms: cream, gel, foam, film, and suppositories. Spermicides immobilize and kill the sperm before they are able to swim into the uterus. Spermicides can be used alone but are more effective when used with another method of birth control, such as a condom or diaphragm. To be effective, the spermicide must be placed deep in the vagina, close to the cervix. Creams, gels, and foams are squirted into the vagina using an applicator. Over the course of 1 year, about 29 out of 100 typical couples who rely on spermicide alone to prevent pregnancy will have an accidental pregnancy. 62 62

Surgical contraception The fallopian tubes and sperm ducts can be cut and tied. 63 63

Natural contraception Natural methods of contraception try to identify the time of ovulation based on: the calendar method – avoiding sexual intercourse during the fertile period the temperature method - monitoring the body temperature, this rises slightly after ovulation. the mucus test. Avoiding intercourse during the female’s fertile peiod. It is not reliable as a form of contraception when used on its own, but it can be helpful both for couples wishing to avoid pregnancy and for those actively trying to have a baby. If a woman's cycle is irregular then natural family planning will be less reliable. 64 64

The Male Pill Uses a combination of testosterone and another sex hormone: progestogen (progesterone). In low doses, in men, progesterone inhibits sperm production in the testes. The drawback is that it can also affect male sexuality and sexual characteristics, so men who take progestogen must also have testosterone injections to maintain those characteristics. Theoretically, the male "pill" would contain both progestogen and testosterone. But because digestion breaks down testosterone, a combination pill couldn't hold enough testosterone to be effective at reversing the effects of the progestogen. So researchers are conducting studies with a progestogen implant combined with testosterone injections 65

Artificial methods Artificial methods of contraception include stopping the female from producing eggs. This can be achieved by taking the contraceptive pill. Other artificial methods include: The use of a condom (covers the top of the penis.

A cap which covers the cervix Chemical creams or foams which kill sperm Medical operations in which the sperm ducts or fallopian tubes are cut and sealed.

Preventing implantation Some pills prevent pregnancy by stopping the embryo from attaching( implanting ) in the uterus. A plastic coil inserted in the uterus also acts in this way.

Some methods of contraception are more successful than others. Some couples decide that a number of these methods are not acceptable to them. This may be because they do not agree with them (morally) or because of religious beliefs. For example some believe preventing implantation is the same as destroying a life.

TWINS Twins account for over 90 per cent of multiple births. Identical twins form when a single fertilised egg (ovum) splits in two. Fraternal twins develop from two eggs fertilised by two sperm, and are no more alike than individual brothers or sisters (siblings) born at different times.

Learning: Doing: About the female and male reproductive systems. Name at least 3 organs of either the female or male reproductive system. Explain the function of both the female or male reproductive system.

Divide the reproductive system parts into male and female. Task: Divide the reproductive system parts into male and female. Match the definitions to the reproductive system parts.

Female Reproduction Ovulation Uterus Cervix Fallopian tubes Vagina Neck or opening to the uterus. Strongest muscle in the body. Fallopian tubes Two tubes which connect the ovaries to the uterus and carry the egg to the uterus. Ovaries Egg shaped Produces female hormones Stores and releases ovum. Ovulation When an egg is released from the ovary and moves down the fallopian tube. Uterus A hollow, muscular organ that protects and nourishes the foetus. Vagina Empty passageway leading from the vaginal opening to the uterus.

Male Reproduction Scrotum Semen Penis Sperm Testicles The organ for reproduction and urination. Scrotum Sacs that regulates temperature for sperm production. Semen A combination of sperm and fluid. Sperm Male sex cell produced by testicles. Testicles Organs in the scrotum that produces sperm and testosterone.

Set out a bingo card in the back of your book or on scrap paper

Choose 9 words and write them in your bingo card fertilisation fallopian tube ovary sperm cervix Semen puberty Scrotum ovulation egg uterus vagina penis testis