School Science Lessons
Sexuality education
Updated: 2009-05-20
Please send comments to: J.Elfick@uq.edu.au
Warning! Before planning to teach any of the content below, get permission from the head of the school science department or the principal of the school.
See also: Sex education for children aged 10 mto 12, Latrobe University, Australia [Needs Flash 6]
Table of contents
10.0.0 Sexuality education
10.1.0 Female reproduction system
10.2.0 Male reproduction system
10.3.0 Puberty and adolescence
10.4.0 Conception
10.5.0 Pregnancy
10.6.0 Relationships
9.9.8a Meiosis in grasshopper testes
9.9.8a Meiosis in grasshopper testes
10.7 Contraception
10.8 Sex safety, reproductive health, sexual health
10.9 Sexually transmitted infections, STIs, HIV and AIDS
10.10 Genital diseases
11.0.0 Drug abuse
10.00 Sexuality education
10.0.1 Design of a school sexuality education programme
10.0.1a Teen girls don't learn how to say no to sex
10.0.2 Research on sexual behaviour of students
10.1.0 Female reproduction system
10.1.1 Female reproductive system
10.1.2 Hormones
10.1.3 Menstruation (periods) ovulation and the menstrual cycle
10.1.4 The first menstruation (period) and sanitary protection
10.1.5 Premenstrual tension, PMT
10.1.6 Vaginal discharges
10.1.7 Menopause, climacteric
10.2.0 Male reproduction system
10.2.1 Male reproductive system
10.2.2 Seminal fluid, semen
10.2.3 Nocturnal emissions
10.2.4 Undescended testicles
10.3.0 Puberty and adolescence
10.3.1 Puberty and adolescence
10.3.2 Puberty in boys
10.3.3 Puberty in girls, the breast
10.3.4 Puberty and skin care
10.4.0 Conception
10.4.1 Conception, the role of the male
10.4.2 Conception, the role of the female
10.4.3 Conception, twins
10.4.4 Conception, sex of the baby
10.5.0 Pregnancy
10.5.1 Pregnancy, changes in the woman
10.5.2 Pregnancy, the embryo stage
10.5.3 Pregnancy, the fetus (foetus) stage
10.5.4 Pregnancy, care of the mother and fetus
10.5.5 Childbirth
10.5.6 After the birth, mental adjustment
10.6.0 Relationships
10.6.1 "Falling in love"
10.6.2 Looking for help, coping with emotions, coping with stress
10.6.3 Sexual feelings in children
10.6.4 Adolescent friendship
10.6.5 Communication with adults
10.6.6 Mood swings, emotional "ups and downs"
10.6.7 "Touching" and "sex play"
10.6.8 Masturbation and orgasm
10.6.9 Sexual feelings of girls
10.6.10 Sexual feelings of boys
10.6.11 Sexual assault, rape, acquaintance rape, date rape, rape crisis centres, domestic violence
10.6.12 Sexuality and the law, laws related to reproductive health of adolescents
10.6.13 Your sexual identity
10.00 Sexuality education
The "facts of life" usually refers to the facts about sex and birth. However, learning about love and how to get on with people is just as important as learning about sex. Young people need to understand their own body, how it works, and how to look after it. So how they feel about themselves and about other people is as important as what they know about the machinery of the human body.
10.0.1 Design of a school sexuality education programme
A school sexuality education programme may contain the physical and emotional changes occurring during puberty, social pressures for dating and becoming sexually active, the desirability and benefits of sexual abstinence, teenage pregnancy, sexually transmitted diseases and HIV/AIDS, date rape, sexual abuse, how alcohol and drug use decrease judgement, sexual activity is never a test of love, class activities to act out ways of resisting pressures to have sexual activity and use drugs, sexuality can be expressed in a variety of ways. School curricula always highlight the need for abstinence. When teaching a sexuality education lesson, keep to the words in the text or the lesson plan approved by a senior colleague. Do not refer to any particular person. Show the prepared diagrams. Do not draw your own diagrams in front of the students. One teaching method that has worked well is to give each student an assignment to prepare a short lecture on a different part of the reproductive system so that all students are taking part in this topic.
10.0.1a Teen girls don't learn how to say no to sex
Sex education in schools is often too little too late an academic says.
Adolescent health specialist Rachel Skinner looked at the sexual experience of 58 girls aged between 14 and 19.
The showed that girls were aware of the consequences of unprotected sex but lacked the negotiating skills to resist peer pressure.
Most respondents said that they regretted their first sexual experience.
Dr Skinner said many of the girls were not prepared when they lost their virginity.
"Many of the teenagers said how sex education was something that was too little and too late in their schooling years", Dr Skinner said.
"These young people knew about risks of unprotected sex ... rather than how to negotiate with a partner about having sex at a time when they feel ready for it."
The Courier-Mail (Brisbane) Wednesday, May 29, 2009
10.0.2 Research on sexual behaviour of students
Sexual intercourse is a necessary part of adult human behaviour if the species is to survive but it is not a necessary part of the behaviour of children or adolescents. Most parents never regard it as acceptable behaviour. Most children or adolescents are minors subject to the authority and responsibility parents and schools acting "in loco parentis" (in the place of a parent). A school sexuality education programme can address the real problems that confront the students only if it is based on knowledge of the sexual behaviour of the students. In many countries, research among adolescents reports an age-related increase in sexual behaviours with most adolescents taking part in sexual activity of some kind.
10.1.1 Female reproductive system
See diagram 10.4.1: Female organs | See diagram 10.4.1a: Ovulation | See diagram 10.4.1b: Menstruation
Women have two glands, ovaries, one on each side in the lower abdomen. Two Fallopian tubes lead from the ovaries to the uterus (womb) then to the vagina and then to the outside. Each ovary produces egg cells, ova, from fluid-filled Graafian follicles scattered through the ovary. The ovum is much bigger than a sperm but it is still very small, about 0.025 mm, you can just see it. Although the ovary is only the size of an almond, each ovary contains 150 000 to 200 000 ova. Every month, from the time of puberty, a Graafian follicle bursts to release an ovum. This release, ovulation, occurs about half way through the menstrual cycle, usually between days 13 and 17. The ovum can be fertilized for about 24 hours after ovulation. The released ovum passes down the Fallopian tube towards the uterus. The uterus (womb) is a hollow, muscular, pear-shaped organ. Before pregnancy it weighs about 60 g, and measures about 9 cm long and 6 cm wide. However, the uterus can enlarge to contain a baby. The lower part of the uterus opens through a narrow neck, the cervix, into the vagina. The vagina is a highly elastic passage, 8 to 10 cm long, leading outside the body. During birth, the baby can pass from the uterus through the cervix and vagina to the outside because the cervix and vagina can expand enough to let the baby pass through. In front of the external opening of the vagina is the clitoris, the sensitive part associated sexual feelings. The labia majora (outer labia) are the large fleshy lips that enclose the entrance to the vagina and the tube leading to the bladder, the urethra. Urine is stored in the bladder until it is passed through the urethra to outside the body. The labia minora (inner labia) are delicate folds of skin that protect the vaginal entrance. They are usually enclosed by the outer labia. During sexual intercourse the cervix produces mucus. Near the time of ovulation, the mucus becomes clear, abundant, elastic and slippery. This mucus helps the sperm to reach the uterus and Fallopian tubes to fertilize the ovum. After a Graafian follicle has burst to release an ovum, it is replaced by a tissue, the corpus luteum or yellow body, that can act as a gland and produce hormones.
10.1.2 Hormones
The male and female sex hormones are all steroids, a group of lipids with four aromatic rings. Puberty starts in boys and girls when the hypothalamus in the forebrain starts to release gonadotrophin-releasing hormone, (GnRH), that stimulates the anterior pituitary gland below it to start releasing gonadotrophin hormones, the follicle-stimulating hormone (FSH), and the luteinizing hormone, (LH). FSH stimulates the formation of sperm in the testes and the development of the Graafian follicles in the ovaries. LH stimulates the testes to produce the main male sex hormones testosterone and androsterone. Also, LH stimulates ovulation, the formation of the corpus luteum in the Graafian follicle after ovulation and the production of progesterone hormone by the ovary. The stimulated Graafian follicle and the corpus luteum produce oestrogen (estrogen) one of a group of female sex hormones that start the development of female sex organs and secondary sex characteristics, e.g. breasts and axillary hair. Oestrogen also stimulates the lining of the vagina that can be examined in vaginal smears. Small amounts of oestrogens are also produced in the adrenal cortex, the placenta and even in the testes. After ovulation, the Graafian follicle continues to secrete the steroid hormone progesterone to prepare the lining of the uterus, endometrium, to receive the fertilized ovum. If a fertilized ovum does not implant in the lining of the uterus, the corpus luteum degenerates and a new Graafian follicle starts to mature. If the fertilized ovum does implant in the lining of the uterus, the corpus luteum continues to produce progesterone that maintains the state of the endometrium, prevents release of ova, and prevents menstruation until after the completion or termination of pregnancy. The placenta produces hormones to maintain the state of pregnancy including progesterone, oestrogens and human chorionic gonadotrophin hormone, (HCG), detected in pregnancy tests. This hormone maintains the release of progesterone by the corpus luteum when the anterior pituitary gland stops releasing gonadotrophin hormones during pregnancy. Progestogens are any group of steroid hormones that have the effect of progesterone to maintain pregnancy. Progestins are synthetic hormones that mimic the action of progesterone.
10.1.3 Menstruation (periods) ovulation and the menstrual cycle
Menstruation, from the Latin "mensis", month, is the monthly flow of blood and uterus lining, endometrium. Menstruation starts on day 1 of the menstrual cycle. Ovulation occurs about half way through the menstrual cycle, on days 13 to 17. During days 15 to 28 the lining of the uterus, endometrium, increases in thickness in preparation for a possible pregnancy. Its lining thickens into a cushion of blood vessels, glands and liquid. If the ovum is not fertilized during days 15 to 28, it does not stick to the wall of the uterus and is washed through the uterus and out through the vagina. On days 1 to 4, menstruation starts by bleeding and the loss of the outer part of the endometrium leaving the base of the endometrium. The loss occurs in spurts or trickles every few minutes until by day 5, at the end of the menstrual period, all the lining of the uterus is lost. The menstrual period usually lasts 5 to 7 days. The volume of blood discharge is 30 to 80 mL but it can be 10 to 210 mL. Probably no girl is absolutely "regular" so the length of the menstrual cycle may be 28 plus or minus 9 days. Being very irregular for the first two or three years is common for a girl's periods. Girls start to have periods during puberty, usually between 10 to 14 years old, about 2 years after the start of breast development, but it can be earlier or later. They continue having periods to the end of their fertile life, i.e. until the menopause. Some girls have regular periods from the first menstruation but other girls are never regular. A regular pattern may not occur until after two years or more. Once the cycle is established, they can expect to continue to have menstrual periods regularly until they are about 50 years. Girls should mark the first day of each period on a calendar and calculate the time between periods from the first day of bleeding. When first menstruating, the time between periods may vary but later a regular pattern develops. Similarly the amount of menstrual discharge may vary. Some girls experience cramps and pain during their periods, dysmenorrhoea. The cramps may be caused by an oversupply of the hormone prostaglandin that causes the uterus to contract to expel the blood and endometrium. To relieve pain during their period, they can try body stretches, exercise or placing a hot water bottle over the abdomen. Girls should be as fit during menstruation as at any other time, so there is no need to behave differently. They can play sport but most women do not like to swim during the period. If they do swim, they should use a tampon. They should not be very active if the period is heavy or if they feel uncomfortable. The best advice to a girl who feels uncomfortable is to "take it easy", have a shower, wash the hair as usual, then rest.
10.1.4 The first menstruation (period) and sanitary protection
The first period usually occurs between 10 and 14 years but it can be earlier or later. Girls should consult a doctor if they have not begun to menstruate by 16 years. Before day 1 of the first menstrual cycle, girls may notice a slight brownish stain in the pants. They should plan for which sanitary protection they will use by asking their mother or a nurse. They should keep the sanitary protection ready at home and carry one or two pads in a small cosmetic purse in the school bag. At school, women teachers understand sanitary protection and will help girls if they are not prepared. Sanitary napkins may be pads worn externally or tampons inserted inside the vagina. Adhesive pads worn inside the usual pants are comfortable and reliable. Tampons are popular with older girls. Some women use both napkins or tampons during the period. Sanitary protection must be changed every three to four hours. Menstrual flow has no odour until it meets the air. A pad or tampon left in place too long may begin to smell and cause infection. Never wear tampons overnight. A tampon worn for longer than eight hours can cause toxic shock syndrome, (TSS). This is an acute illness with a sudden onset of high fever, vomiting, abdominal pain, diarrhoea, headache, muscle pain and rash. Before using tampons, read the instructions on the packet. Wash the hands before, and after, inserting tampons. Store tampons carefully and insert them gently. Use of a hand-held mirror makes insertion easier. Leave the string hanging out to make removal easier. Remember to remove the last tampon when the period is finished.
10.1.5 Premenstrual tension, PMT
Girls may have an uncomfortable "dragged down" feeling low in the stomach or pelvic area just before a period begins, and for the first 12 hours after the period has started. Some girls say they feel bloated, and they can weigh more. These symptoms usually soon disappear after the period. The sweat glands are more active during menstruation so personal cleanliness is more important at this time. Some girls experience loose bowel motions just before a period but constipation is more common. At this time they should drink more water, eat extra fruit and fresh, vegetables, eat wholemeal bread, and exercise regularly. They do not need to use laxatives. Some girls experience cramping and pain during their periods (dysmenorrhoea). This cramping may be caused by an oversupply of the hormone prostaglandin that causes the uterus to contract during menstruation. If they have pain during the period, they may find it helpful to do some stretches, exercise or yoga, or place a hot water bottle over the abdomen.
10.1.6 Vaginal discharges
At puberty, the walls of the vagina thicken and vaginal secretions are produced as a slight discharge. Girls may notice differences in the secretions at different times between menstrual periods. At the time of ovulation, the mucus may be thinner, clearer, and "stringy", slippery like egg white. This is normal and healthy. The vagina is self-cleaning so do not use perfumed sprays on the vagina. Do not use plastic-backed panty shields because they do not allow adequate air to circulate, and may provide a breeding ground for bacteria. Consistent, heavy vaginal discharges may indicate an infection. A thick, white discharge with a yeasty smell is a symptom of Candida albicans, (thrush). This is a common condition that can be easily treated easily by a doctor or nurse. However, sexually transmitted diseases can also cause vaginal discharge so girls should see a doctor or nurse if the discharge is unusual.
10.1.7 Menopause, climacteric
The menopause, climacteric, is the time the ovaries stop producing eggs, menstruation stops and the woman becomes infertile. It usually occurs at about 50 years. This change of life is a normal and natural event. However, the hormone imbalance that occurs with the slowing down of ovarian function can produce mood swings, irritability, hot flushes, loss of sex drive and loss of self-esteem. Long-term effects of lack of oestrogen may cause osteoporosis, bone thinning in elderly women. Some doctors prescribe hormones to help women during menopause, but other doctors do not prescribe hormones because of possible side-effects.
10.2.1 Male reproductive system
See diagram 10.11: Male reproduction organs
The testes (testicles) manufacture and secrete the hormone testosterone. Testes contain cells that begin to form sperm, spermatozoa, in long tubules, the seminiferous tubules. The spermatozoa then move along a long coiled tube, the epididymis, where they become mature and are stored ready for ejaculation. After ejaculation in the semen, the sperm can fertilize an ovum for about 72 hours. The epididymis connects the testis to the vas deferens that connects to the urethra that runs through the penis. The spermatozoa need a liquid to swim in and some nourishment. This is provided by the seminal fluid, the semen. Two seminal vesicles, male sex glands, open into the vas deferens before it joins the urethra. They produce most of the liquid in semen. Also, the nearby prostate glands and Cowper's glands (bulbourethral glands) add fluid to the semen. The temperature of the testicles should be lower than body temperature for the sperm to develop normally so they hang outside the body in a bag, the scrotum. Wearing tight trousers for a long time may damage the production of sperm. It is quite normal for a boy's two testicles to be different sizes. The penis contains a rich blood and nerve supply. It can change from being small and soft to being hard and erect when spongy tissue in the penis, corpus cavernosum and corpus spongiosum, fills with blood and cause the erection of the penis. Erection ("hard-on", "stiffie") occurs when a man is excited sexually. The penis of humans does not contain any bones and is not made of muscle. The foreskin is a fold of skin that protects the glans penis at the end of the penis. The skin beneath the foreskin must be kept clean. The foreskin should be pushed back daily and the glans washed. The foreskin may be removed surgically in infant boys by circumcision. Circumcision is required by some religious beliefs. The seminal vesicle secretes an alkaline fluid that forms the bulk of the semen. The prostate gland also secretes fluid that is part of semen. The semen passes through tubes called the epididymis, vas deferens and urethra. During normal activity, urine from the bladder passes down the urethra and through the penis to the outside. However, when the male becomes sexually excited, spongy tissue in the penis fills with blood so that the penis becomes longer and erect. During sexual intercourse, the sperm swimming in the liquid semen are discharged quickly into the vagina of the female. The sperms travel through the uterus and up the Fallopian tube because of their swimming motion, and perhaps contraction in the Fallopian tubes, to fertilize an ovum or die.
10.2.2 Seminal fluid, semen
At peak sexual excitement, semen is quickly pumped out of the end of the urethra in an erect penis. This is called ejaculation or "coming". Each ejaculation from the penis contains 200 to 500 million sperm in a seminal fluid, the semen. The thick white seminal fluid is secreted by glands, prostate gland, seminal vesicles and Cowper's gland. It contains sugars to nourish the sperm and prostaglandins that act like hormones to cause contraction of the smooth muscle in the vagina. Each sperm, spermatozoon, can only be seen under a microscope. Each spermatozoon looks like a tadpole with a head, middle piece and tail to help it swim. Muscular movement of the vagina during sexual intercourse may help the sperm to travel from the vagina into the fallopian tubes. Both semen and urine can pass through the urethra but they can never pass along it simultaneously because a sphincter muscle holds back urine when the penis is erect.
10.2.3 Nocturnal emissions
During puberty, boys can easily become sexually aroused and ejaculation can occur while they are asleep. These nocturnal emissions, "wet dreams", are the natural way of discharging excess semen. After a nocturnal emission the sheets or pyjamas may feel sticky when the boy wakes after a sexually exciting dream or a nightmare or sometimes remembering nothing about it. The boy should not be ashamed of any stain on the bed linen. It can be removed by washing in cold water or by normal machine washing.
10.2.4 Undescended testicles
Testicles begin to develop in the lower part of the abdomen long before a boy is born. Shortly before birth, they move down through the two inguinal canals to the scrotum. Sometimes one or both testes remain either in the abdomen or in the inguinal canal. This is called an undescended testicle. Take a baby boy to the doctor if he does not have two testicles in the scrotum. Testicles that have descended normally will sometimes retract into the body but they may move back into place.
10.3.1 Puberty and adolescence
Adolescence is the process of becoming adult. Puberty is the period when a growth spurt occurs for 2 to 3 years and the reproductive organs develop. The sweat glands may produce a thickened sweat during stress, strong emotions or sexual excitement and cause an unpleasant body odour. Before puberty the pituitary gland at the base of the brain begins to produce hormones that cause changes throughout the body. In boys, the testes (testicles, balls) start to produce the male hormone, testosterone. In girls, the ovaries start to produce the main female hormone, oestrogen. Some boys and girls are frightened by the changes that occur during puberty but other are very interested in the changes during puberty that are producing "a new you".
10.3.2 Puberty in boys
In boys, puberty usually begins between the ages of thirteen or fourteen years, but the whole process takes three or four years until they are physically mature. They growing taller and perhaps broader and more muscular. They may feel awkward, with arms and legs that seem too long. Hair appears on the chin, upper lip, under the arms, in pubic area and perhaps on the chest and other parts of the body. The larynx, "Adam's apple", gets bigger. The voice begins to "break" when the vocal chords become longer and thicker and vibrate more slowly to produce a deeper sound. They may be embarrassed by a voice that squeaks unexpectedly before it settles to its new, lower pitch. They may develop acne (pimples) on the face and neck, caused by inflammation of the sebaceous glands. However, acne can usually be cured with careful facial cleanliness and medical treatment. The testicles and other sex organs become larger. If they have sexual intercourse with a girl any time after puberty begins, they could make her pregnant. They may compare their body with the bodies of other boys and be worried if they see another boy of the same age who has a larger penis or more hair or bigger arm and leg muscles. They may wonder whether they will ever catch up with these physical attributes. However most boys realize that different boys pass through the events of puberty things in a different sequence and at a different rate. So each boy has his own biological programme of development.
Both boys and girls should eat plenty of fresh fruit and vegetables and reduce fatty and sugary foods such as pastries and sweet biscuits. They should avoid crash diets and enjoy regular exercise, sport, and dancing.
10.3.3 Puberty in girls, the breast
See diagram 10.3.3: Mammary gland, breast, vertical section
Girls usually begin puberty earlier than boys, usually between 8 to 13 years. The breasts begin to develop "breast buds" with a dark area around the nipple, the areola, and the body becomes more rounded as fat is deposited under the skin at the hips, thighs and buttocks. Hair begins to grow under the arms and around the pubic area. They start to have menstrual periods, a sign that the reproductive organs are maturing. Some girls feel strangely top heavy and wish they did not have to worry about wearing a brassiere. The nipple area of the breast is sexually sensitive and under the region under the nipples may feel sore. Breasts vary in size and shape. The smaller breast feeds the baby just as well as a larger breast. Each breast contains alveolar glands that secrete milk, lactiferous ducts that take the milk to the nipple and fatty tissue. The first sign of puberty is usually a surge of growth they become taller, the breasts develop, hair begins to grow under the arms and as an inverted triangle in the pubic area. The bones in the face may grow to change a round face to an oval face. Growth of pelvic bones may result in wide hips. They will probably experience mood swings, partly because of all the hormonal activity, and partly because they are becoming a young adult. It takes time to get used to the idea of being a woman. They must cope with new sexual feelings, perhaps even the intense feeling of being "in love". Girls with dark hair may notice extra hair on the upper lip but it may not last. They develop the adult female shape, the hips widen slightly, the thighs become more rounded and the breasts develop. Any time after the beginning of puberty, the body may start to produce ova (eggs). If an ovum (egg) is fertilized by a male sperm, they could become pregnant or "in the family way".
Both boys and girls should eat plenty of fresh fruit and vegetables and reduce fatty and sugary foods such as pastries and sweet biscuits. They should avoid crash diets and enjoy regular exercise, sport, and dancing.
10.3.4 Puberty and skin care
The new sex hormones developing in adolescents' testes or ovaries affect the sweat glands, that produce sweat, and sebaceous glands, that produce oily sebum. The best way to stop a sweaty smell is to use plenty of soap and water. Deodorants may help, but excessive use of antiperspirants is not good for the body. They should shower at least once per day. Acne, acne vulgaris is caused by extra activity of the sebaceous glands in the skin that produce sebum, a natural oil that keeps skin supple. Hormones active during puberty make the sebaceous glands produce extra sebum that can clog the pores of the skin by forming plugs. The sebaceous glands keep producing sebum that cannot get out because of the plug and that region of the skin becomes inflamed and tender. The plugs of sebum form pustules called "white heads" which may form "black heads" when contacted by air. There is no single treatment for acne to suit everybody. However, a doctor can usually find a successful medical treatment. Frequent gentle washing with water and a mild soap usually helps. Use an astringent (drying) face lotion, rather than one containing oil. Eat plenty of fresh fruit and vegetables and less of any foods that seem to make acne worse, e.g. chocolate. If the white head or black ahead acne pimples are squeezed, the sebum leaks into the skin causing more inflammation and may make it easier for other infections to get into the skin.
10.4.1 Conception, the role of the male
When a man is sexually excited, his penis becomes hard and erect and grows bigger because of extra blood flow into the penis. In humans the penis contains no bones and is not made of muscle. If he has a climax, or "comes" when his penis is inside the woman's vagina, millions of sperm are released at the time of ejaculation. These sperm move into the uterus and then the Fallopian tubes. A baby is conceived if the head of a sperm unites with an ovum and fertilizes it. Normally, an ovum is released about every 28 days, 14 days before the beginning of the next period. The ovum takes 3 to 6 days to travel down the Fallopian tube and reach the uterus. If just one sperm enters the ovum while it is in the Fallopian tube or uterus the ovum is fertilized. The rest of the sperm die within two or three days. Any time they have sexual intercourse a baby could be conceived. During sexual intercourse, if the penis is in the vagina or even close to the female genital area, some semen may escape into the vagina, even if the male does not reach orgasm.
10.4.2 Conception, the role of the female
Ovulation is the release of an ovum from an ovary about 14 days before a period. Conception usually occurs a short time after ovulation. However, ovulation can be influenced by stress, illness, sexual excitement or changes in routine. Therefore, usually, predicting the time when a baby is likely to be conceived is difficult. Conception occurs if a sperm from a male fertilizes an ovum in a Fallopian tube. During sexual intercourse a man inserts his penis (the male sex organ) in a woman's vagina and ejaculates ("reaches a climax", "comes") 1 to 2 teaspoons of semen containing millions of sperm. After girls start menstruating, and sometimes even before, they can become pregnant if any semen is deposited in or even just outside the vagina. It is not necessary for either or both sexual partners to reach orgasm for conception to occur. The bodies of men and women undergo a similar experience during sexual arousal. Blood flows to the man's penis to cause an erection and to the woman's vaginal area to make it soft and moist. The heartbeat and breathing quicken leading to orgasm, climax, when the increasing arousal leads to spontaneous contractions in the muscles around the penis, ejaculation, and in the vagina, accompanied by pleasant erotic sensations. These contractions help drive the semen through the man's penis into the woman's vagina and through the vagina, uterus and Fallopian tubes.
10.4.3 Conception, twins
About one in ninety pregnancies results in twins. Identical twins are the result of one ovum dividing into two after it has been fertilized. Each half develops separately and two babies are born. Because both come from the same ovum and sperm, they are always the same sex and usually look very alike. The non-identical twins, "fraternal twins", are the result of two ova being fertilized at about the same time by two different sperms. These twins can be the same or different sexes and are no more like each other than ordinary brothers and sisters. Twins occur by chance although some families seem to have a history of twins.
10.4.4 Conception, sex of the baby
The sex of a baby is determined when it is conceived. The two types of chromosomes are the X chromosome and Y chromosome. A woman's chromosomes are always X. The cells of her body each contain twenty two pairs of XX chromosomes and one pair of XX sex chromosomes, which make her a woman. However, her ovum contains twenty two X chromosomes and only one of the pair of X sex chromosomes. The cells of the man's body each contain twenty two pairs of XX chromosomes and one pair of sex chromosomes consisting of one X sex chromosome and one Y sex chromosome. The sperm from the male carries twenty two X chromosomes and either one X sex chromosome or one Y sex chromosome. If the sperm carries a Y sex chromosome, the baby will have one X sex chromosome from the mother and one Y sex chromosome form the father, so the baby is a boy. If the sperm carries an X chromosome, the baby will have two X sex chromosomes, one X sex chromosome from the mother and one X sex chromosome from the father, so the baby is a girl. It is just a matter of chance, whether a sperm carrying the X sex chromosome or the Y sex chromosome fertilizes the ovum. However, the sex ratio at the time of birth, secondary sex ratio, is 105 boys to 100 girls.
10.5.1 Pregnancy, changes in the woman
See diagram 10.23: Fertilization
The start of pregnancy is conception when a sperm fertilizes an ovum usually in the upper end (ovarian end) of the Fallopian tube (oviduct). The final stage of meiosis occurs and the fertilized ovum starts dividing to form the embryo that keeps moving down the Fallopian tube to the uterus. Usually it sticks to the lining of the uterus, implants, where it absorbs food and oxygen. The lining of the uterus becomes thicker and stays there so it is not lost by menstruation. For most women, the first sign of being pregnant is when the menstrual periods stop. Menstruation does not occur until after the baby is born. An organ forms to attach the embryo to the inner wall of the uterus, the placenta, and absorb food and oxygen from the mother and take away the wastes from the baby. About eight weeks after conception the main organs have formed and the embryo is then called a fetus (foetus). The fetus is joined to the placenta by the umbilical cord that contains two arteries to carry blood to the placenta and a vein to carry blood back to the fetus. So the mother provides food and oxygen to the fetus and excretes wastes from the fetus through her lungs and kidneys. However, the mother's circulatory system is quite separate from the circulatory system of the fetus so her blood does not mix with the blood of the unborn baby. Oxygen and nourishment are exchanged by diffusion in the placenta.
10.5.2 Pregnancy, the embryo stage
See diagram 10.24.1 Pregnancy 1 | See diagram 10.24.2: Pregnancy 2 | See diagram 10.24.3: Pregnancy 3
The fertilized ovum completes meiosis and starts dividing and the cells keep dividing until a hollow ball of cells, the blastocyst forms. During this process the embryo is floating freely down the Fallopian tube until it enters the uterus. Six to eight days after ovulation the blastocyst becomes attached to the wall of the uterus, implants, and the placenta forms at the place of attachment. The placenta allows transfer of  oxygen and nutrients from the mother to the foetus and wastes from the foetus to the mother.
10.5.3 Pregnancy, the fetus stage
See diagram 10.25.1: Pregnancy 4| See diagram 10.25.2:  Pregnancy 5 | See diagram 10.26: Just before birth
The baby develops during the 40 weeks of pregnancy At the fourth week, the embryo is 7-8 mm long and has a distinguishable head and body. Little buds begin to develop where the limbs will grow. This is the stage when the embryo is very sensitive to diseases, e.g. rubella, or chemicals, e.g. thalidomide. The head is about a third of the total size of the embryo. At the sixth week, the embryo is 1.3 cm long and floats in a "watery sac" of amniotic fluid that protects it from bumps and shocks. Blood vessels can now be seen in the umbilical cord through which blood travels to and from the placenta. After the eighth week the embryo is called a foetus (fetus). It is now about 3 cm long, and real bones begin to develop to replace cartilage. Most body organs such as heart and liver have appeared but they are very immature. The eyes of the fetus are shut and do not open for many months. After the sixteenth week the fetus is about 18 cm long. It is quite active, and they can feel it kicking and stretching its arms and legs. After the twenty eighth week the fetus is nearly 30 cm long and hair and nails have developed. The skin has produced a creamy coating (vernix) which protects it from the effects of being immersed for so long in salty water inside its sac. Between week twenty eight and week forty, the fetus develops and grows bigger.
10.5.4 Pregnancy, care of the mother and fetus
Choose a healthy diet when planning a pregnancy and avoid smoking. Reduce the use of medications during pregnancy to a minimum, as prescribed by a doctor. The rapidly developing tissues of the embryo and fetus are sensitive to the effects of all drugs, including alcohol and tobacco. The placenta is not a barrier to the passage of most drugs. The health risks associated with non-medical drug use during pregnancy include low birth weight, complications during pregnancy and prenatal mortality. The baby may be born addicted to a drug taken by the mother. Do special exercises during pregnancy to train the abdominal muscles.
10.5.5 Childbirth
See diagram 10.27: Birth
1. The baby is born about nine months, 40 weeks, 280 days, after conception.
2. The whole process of labour takes about 12 hours for first mothers and less for later mothers. At the beginning of labour the muscles in the wall of the uterus start to contract and the muscles in the cervix relax, so it can expand. The mother is then "being in labour". These contractions become more frequent and intense as the birth gets closer. The amnion membrane that enclosed the baby in the uterus pushes out through the cervix and breaks under the pressure from the contacting uterus to release amniotic fluid (the breaking of the waters). The head of the baby moves into the cervix because of the increased contractions of the uterus helped by contractions of the muscles in the abdomen and pushing contractions controlled by the mother. The cervix gradually opens and the vagina stretches to let the baby pass through. The baby is pushed through the vagina until the head can be seen and the mother can be given help to expel the baby from her body. A baby is usually born head first. If it is born buttocks first, this is called a "breech" birth.
3. When the baby is born, the umbilical cord still connects the baby to the placenta still inside the uterus. After the baby has been born, the doctor or midwife ties or clamps the umbilical cord and cuts it about five centimetres from the baby and ties the cut end into a knot. The short piece left attached to the baby dries up and usually drops off within a few days. The place where it was attached heals and leaves a depression in the abdomen of the baby, the navel (umbilicus, omphalus, "belly button").
4. Within two hours after the birth, the umbilical cord, the placenta and ruptured membranes (afterbirth) that have been surrounding the baby, separate from the wall of the uterus and come away through the vagina. A doctor or nurse should check that the afterbirth is entire and none of it is left behind in the vagina.
5. The baby is almost helpless when it is born so the mother must care for it. Soon after birth the baby should be put to the mother's breast to suck milk. Breast milk is the best milk for babies unless the mother has certain diseases. The mother should feed the baby with her milk for as many months as possible. Early breast milk, just after the birth, is most important because it contains colostrum that helps the baby to establish an immune system to protect against disease. Mothers who are breast feeding should not take aspirin because it can be passed to the feeding baby and cause Reye’s Syndrome, a potentially lethal disease of the liver and brain.
6. The baby should be placed to sleep on the back and not allowed to sleep face down  (prone sleeping) to avoid the possibility of Sudden Infant Death Syndrome (SIDS).
10.5.6 After the birth, mental adjustment
1. Adjusting it to being responsible for another human being 24 hours a day is not easy. Postnatal depression, "baby blues", fleeting feelings of misery and helplessness is common in mothers after the birth of the first baby. It soon goes away especially if the partner is sympathetic and helpful. However, extreme depression after giving birth may need medical treatment.
2. A new mother may feel very insecure and unattractive but daily postnatal exercises can help to restore her self-image. Pelvic floor exercises can repair any vaginal slackness caused by the stretching of the pelvic floor muscles during pregnancy and delivery.
3. Breasts will not be as firm, whether breast-feeding or not. Brown skin colour around the nipples and the brownish vertical "tummy stripe" developed during pregnancy may take four months to fade. Stretch marks fade gradually to become silvery lines.
4. Breast-feeding alone is a natural contraceptive for one third of women, but up to 20% of breast-feeding women ovulate and could conceive within 12 weeks of giving birth.
5. During pregnancy and particularly soon after the birth of a baby, some women prefer to be held and cuddled rather than have sexual intercourse. After the birth, the best time to resume sexual intercourse is when both partners feel they are ready and on medical advice. If lack of oestrogen soon after the birth in a breast-feeding mother causes dryness in the vagina, she should use a water-based lubricant. Fatigue caused by broken nights and busy days may reduce the sexual interest of parents. However, intimacy does not have to result in intercourse.
10.6.0 Relationships
10.6.1 "Falling in love"
Falling in love is one of the most wonderful and exciting experiences life has to offer. However, learning to cope with this intense feeling can be even more difficult than learning to cope with new sexual feelings. Love can be so exciting that it seems to take over the whole life. However, most people "fall in love" more than once before they find a permanent sexual partner. They should ask themselves: "Is this relationship a sharing and caring one?", " Do we have common interests and enjoy the same activities?", "Are they both able to talk and listen to each other?", "Do we both care about the other and the way he or she feels?". Talk over their feelings with an adult they can trust.
Being in love may be caused by the amine dopamine that acts as a neurotransmitter and hormoneDopamine has many functions in the brain. . It is produced in women after giving birth and is secreted into the body as a result of taking narcotic drugs.
10.6.2 Looking for help, coping with emotions, coping with stress
Feeling depressed can mean that you feel sad, guilty, exhausted, lost, hopeless, powerless. Feeling depressed and having clinical depression is not the same. You can feel depressed if you do not get a job or an expected reward or if a relationship breaks up. Sadness is a normal human emotion felt when you lose something or someone. It does not take over your whole life like clinical depression can. The symptoms of clinical depression may be feeling depressed for most of the day nearly every day, being continually irritable, having diminished interest or pleasure in all or most activities, more than 5% change of body weight, feelings of worthlessness or inappropriate guilt, diminished ability to think or concentrate, recurrent thoughts of death or suicide, an attempt at suicide. Many people have suffered from clinical depression at some time in their lives so it is nothing to be ashamed about. So if you have these symptoms do get medical help.
10.6.3 Sexual feelings in children
Most societies treat male children differently to female children and have different expectations of the behaviour of each sex. Parents should treat a child's genital play or toilet training with calm acceptance of a natural part of life. Boys and girls will express an interest in the differences in the sexes. In the early years children may ask "Where do babies come from?". In late childhood they may be curious about changes that occur in puberty. By the middle of childhood, boys and girls often segregate themselves in play and develop a collective opinion about the opposite sex. By the age of five years a child becomes very aware of the physical sexual differences between boys and girls. By the age of six years, a child may display some interest in sex play through games such as "doctors and nurses" or "mummy and daddy". By the age of seven years, girls to want to play with other girls and boys with boys. Boys may say that they want to avoid "girl germs". Among friends they may express their dislike of the opposite sex. At eight years of age growth hormones are beginning to be released leading to puberty still some years away. By about nine or ten years of age sex will become a keen interest and a child will want to discuss it with friends and will look for illustrative material that describes or displays the human body. In late childhood there can be growing shyness or self-consciousness of a child's own naked body. All of these childhood experiences give a child a picture of sex. However, a child should in addition receive sound information to be prepared for puberty and adulthood.
10.6.4 Adolescent friendship
Adolescents may find that the friendships with other boys and girls become more intense at this time. It is important to be able to talk and listen, care about others and care about other peoples' feelings. They may lack confidence and feel unsure of themselves. However, most other boys and girls of this age have the same problems. Life is easier for them if they have a group of friends, boys and girls, who enjoy the same activities. Around 13 to 14 years, girls are usually taller than boys of their own age so they feel awkward.
10.6.5 Communication with adults
Keeping communication lines open with the adults who care for they can help to avoid many problems. As they grow and change, the relationships with different members of the family will probably change. They must take a greater role in making decisions and being responsible for themselves. Making this change can be difficult for parents and other adults who are used to doing these things for them. Sometimes adolescents just do not have the understanding or experience to decide on what is acceptable behaviour. The family's lifestyle, cultural background and religion will affect their feelings about what adolescents may do and where they go. Some families have inflexible rules, but others do not. Adolescents should try talking matters over with the parents. If this is really too difficult, they should discuss their problems with a school counsellor or another adult they respect. If they can talk about the problems, they will be easier to solve.
10.6.6 Mood swings, emotional "ups and downs"
Young people may feel more emotional during puberty. They may experience "mood swings", wildly happy then miserable. Mood swings may occur from one extreme to the other. One minute they may feel aggressive and full of confidence, then the next minute they may feel uncertain and unsure of themselves. They may feel cheerful and outgoing, then, for no apparent reason, feel moody and withdrawn. These changes of feelings are normal. However, mood swings may make it hard to get along with other members of the family. There may be arguments over how to divide the time between study and fun, the hours to keep, the friends to choose, the clothes to wear or even the hairstyle.
10.6.7 "Touching" and "sex play"
"Touching" and "sex play" are not harmful in themselves, but they can stir up sexual excitement that is hard to control. A girl can become pregnant the first time she has intercourse after puberty begins. The best rule for adolescents is never to get into a situation where they feel they might be persuaded to do something that they do not want to do, or that goes against their conscience. In some societies, a girl is never allowed to be alone in a room with a man unless he is her father or husband.
10.6.8 Masturbation and orgasm
A boy masturbates by stroking or rubbing his penis, usually until ejaculation. It is a way of relieving sexual tension. Some boys get very worried if they get into the habit of frequent masturbation. The practice should not cause any physical or mental harm unless carried to excess. Girls masturbate by caressing or rubbing the clitoris, often until they reach orgasm. Orgasm is the climax of sexual excitement. A man usually reaches this climax when he ejaculates. However, a woman may have an orgasm during intercourse or when her clitoris is being stimulated. Having an orgasm is not at all related to conception of a baby. A woman can still become pregnant whether or not she has had an orgasm.
10.6.9 Sexual feelings of girls
Sexual excitement may lead to a feeling of moisture at the entrance of the vagina, "down there". Fluid is produced by two small glands so that, in sexual intercourse, the penis can enter the vagina without causing discomfort. Adolescent girls are often physically ready for sexual relationships before they are mature enough to handle them. They have nothing to fear by saying "NO!". Individuals in a group do things they would prefer not to because they do not want to be different from the rest. They must not put themselves at risk of pregnancy or contracting a sexually transmitted diseases. If they do start sexual activity they should learn the proper way to use a condom before the first act of sexual intercourse. The risk of sexually transmissible diseases increases with the number of sexual partners. When the periods start, and occasionally just before, women can still become pregnant, so there is no "safe period".
10.6.10 Sexual feelings of boys
Boys can be sexually aroused and have an erection anytime, and for many reasons. They could be turned on by the sight of a girl or by thinking about something sexually exciting or by kissing, touching, stroking, and even tight clothing. At first, these erections may be embarrassing. They should try to think about something else or go for a run or any other physical activity. Many men wake up in the morning with an erection due to hormone activity when asleep. After urinating the erection goes away. Adolescent boys can have sexual relationships before they are mature enough to handle them. However, they should not be in a hurry to start sexual activity. People in a group may do things they would prefer not to because they do not want to be different from the rest. However, they do not have to act in the same way as the friends do. Saying "No" to sexual intercourse is the only guaranteed way not to put themselves at risk of causing pregnancy of becoming infected with a sexually-transmitted disease.
If they do start sexual activity they should learn the proper way to use a condom before the first act of sexual intercourse. Boys should practise how to put on and take off a condom. In many countries, it is against the law for anyone to have sexual intercourse with a girl if either of them is less than 16 years of age.
10.6.11 Sexual assault, rape, acquaintance rape, date rape, rape crisis centres
Rape can be defined as:
1. Where a person is incapable, because of a mental disorder or developmental or physical disability, of giving legal consent, and this is known to the person committing the act. The prosecuting attorney shall prove, as an element of the crime, that a mental disorder or developmental or physical disability rendered the alleged victim incapable of giving consent.
2. Where it is accomplished against a person's will by means of force, violence or fear of immediate and unlawful bodily injury on the person or another.
3. Where a person is prevented from resisting by any intoxicating or anaesthetic substance, or any controlled substance, administered by or with the privacy of the accused.
4. Where a person is at the time unconscious of the nature of the act, and this is known to the accused.
5. Where a person submits under the belief that the person committing the act is the victim's spouse, and this belief is induced by any artifice, pretence, or concealment practised by the accused, with intent to induce the belief.
6. Where the act is accomplished against the victim's will by threatening to retaliate in the future against the victim or any other person, and there is a reasonable possibility that the perpetrator will execute the threat. As used in this paragraph "threatening to retaliate" means a threat to kidnap or falsely imprison, or to inflict extreme pain, serious bodily injury, or death.
7. Where the act is accomplished against the victim's will by threatening to use the authority of a public official to incarcerate, arrest, or deport the victim or another, and the victim has a reasonable belief that the perpetrator is a public official.
Domestic violence refers to recurring patterns of sexual violence where the male appears to be unaware that his behaviour was violent and the female may even accept such behaviour as normal or think she cannot escape it. Domestic violence is the physical, sexual, emotional or psychological abuse of trust and power between partners in a spousal relationship. Most domestic violence is perpetrated by men against women. In Australia, domestic violence is the leading cause of injury to women of reproductive age, the single most common trigger of female suicide, implicated in over 60% of the murders of women, a major cause of maternal mortality (death during pregnancy or in the months after childbirth).
10.6.12 Sexuality and the law
In many countries, the age of consent for homosexual and heterosexual sex is 16 years but it may vary in different states of a country. The only defences that might be accepted are usually closeness of age, e.g. a 17 year old and a 15 year old, or the belief that the other person was over the age of consent. For example in the United Kingdom (UK) it is against the law for anyone for a boy to have sexual intercourse with a girl if either of them is less than 16 years. It is an offence for a boy or man to have sexual intercourse with a girl less than 16 years, even if she agrees. Her sexual partner is breaking the law. Girls, unlike boys, cannot be prosecuted for having sexual intercourse if they are less than 16 years. A woman who has sex with a boy who is less than 16 years can be prosecuted for indecent assault. If the girl is less than 13 years, the maximum penalty is life imprisonment. It is no defence for the boy to say in court that the girl "wanted it". For men, the age of consent for male gay relationships is 18 years. A sexual relationship between men younger than this is illegal. Sexual contact between men is permitted only if both men consent, are 18 years or over, and it takes place in private with no one else present.
10.6.13 Your sexual identity
The following information is offered by the Health Queensland (Ministry of Health, State of Queensland, Australia)
We all get a wide range of messages about sex and relationships from family, friends, magazines and other people around us like church groups or community leaders. Sometimes these messages are very different. You may have heard of the terms heterosexual, homosexual and bisexual.
A heterosexual person is attracted to people of the opposite sex. Most people are heterosexual.
A homosexual person is attracted to people of the same sex. Sometimes words like gay (for men) and lesbian (for women) are used. Because these words are often used in a hurtful way, not everyone who is homosexual wants to be given these labels. About 10% of the population identifies as either being gay or a lesbian.
A bisexual person is attracted to people from both sexes. It is not clear what percentage of the population is bisexual.
Whatever your sexual orientation, whether you see yourself as straight, gay, a lesbian or bisexual, it is important to understand that no form of sexual orientation is unlawful. Some people have strong feelings about sexual orientation. Our society encourages, expects and conditions most people to be heterosexual. People who are different often experience discrimination. In Australia, anti-discrimination law protects the rights of individuals and unlawful discrimination can be addressed through the legal system.
It's OK to be you. It's OK for others to be themselves too. Respecting others and accepting them is an important way of ensuring that our communities are safe places for everyone.