Sexual reproduction in humans

Transcription

1 Sexual reproduction in humans Name: WHY DO HUMANS NEED TO REPRODUCE? The reason humans reproduce is to have children so that our species can continue to exist. Humans reproduce sexually, which means like angiosperms, a male gamete (called a sperm) carrying half of the male DNA must join with the female gamete (called an egg) carrying half of the female DNA. When they fuse, the DNA combines to form a new, complete set of DNA in the zygote which grows into a new human baby. Our sexual organs are designed to make this process possible. Puberty In Grade 7, you may notice that your body and the bodies of your classfriends are changing. This stage of life is called puberty. Physical Changes Here is a table that compares the physical changes that happen in boys and girls as they go through puberty. AGE Maturing of reproductive organs Hormones Body shape Hair growth GIRLS YEARS OLD Vagina, uterus, ovaries Increased release of oestrogen and progesterone Hips widen, more defined waist, development of breasts, increase in body fat Under arms, pubic area BOYS YEARS Penis, testicles Increased release of testosterone Increase in size of bones and muscles, stronger and more built Under arms, pubic area, face and chest. Voice Deepens slightly Deepens and lowers Body odour Acne / Pimples Changes, becomes stronger because of more oils in skin and change in the smell of sweat. More oil in skin and changes in hormones

2 Emotional Changes Many of the emotional changes that boys and girls going through puberty experience, are due to the changes in hormone levels but also relate to changes in their social relationships as well. This is a list of a few commonly experienced emotional changes: Strong feelings More sensitive More self-conscious Seek new experiences (which often leads to dangerous risk-taking behaviour) Exploring sexual identity Changes in reproductive organs A male s reproductive organs include the penis and two testes enclosed in the scrotum (pouch of skin). During puberty, the scrotum, testes and penis grow larger. The testes mature and begin to produce sperm (the male gamete). A female s reproductive organs include the vagina, the uterus, two fallopian tubes (oviducts) and two ovaries. During puberty, the uterus becomes longer and the lining of the uterus thickens. The ovaries mature and release one mature egg (female gamete) every month in the process called ovulation. (All girls are born with a number of eggs in each ovary and only at puberty when they mature, are they released.) Male reproductive system Female reproductive system sperm tubes urethra penis bladder prostate anus endometrium (lining of the uterus) uterus fallopian tubes (oviducts) ovary cervix vagina vulva testes scrotum

3 STAGES IN HUMAN REPRODUCTION At this age, you are not ready for the responsibility of having a baby and becoming a parent, but your body is maturing and being prepared for reproduction. These are the stages of how an egg and sperm fuse to form a new human baby. Ovulation Once a month, the ovaries in a girl s body release one egg. It moves from the ovary into the fallopian tube (oviduct). The egg travels down the fallopian tube and into the uterus. During its travels, the egg may become fertilised by the sperm. Throughout this process, the lining of the uterus thickens and becomes filled with a good blood supply to prepare for the fertilised egg to implant into it and to provide the growing cells with oxygen and nutrients. Uterine lining is shed New egg matures and uterine lining begins to thicken Egg released Uterine lining thickens further Unfertilised egg passes through uterus Fertilisation During sexual intercourse, the male releases millions of sperm cells into the female s vagina. These sperm swim up into the uterus and into the fallopian tubes. When the sperm reach the egg, they try to fuse with it. Only one of them will enter through the outer layer of the egg. Once this has happened, no other sperm can fuse with the egg. The moment that the sperm and egg fuse is called conception. The new baby is conceived even though at this stage it is only one little cell. This cell will grow into a baby.

4 Pregnancy Fertilisation can happen in the fallopian tube or in the uterus. The new cell moves to the uterus and implants (attaches itself) to the lining of the uterus. There it grows and develops into a baby over 9 months. A placenta forms in the uterus and an umbilical cord develops which connects the baby to the placenta in the uterus. This placenta and umbilical cord supply the baby with the nutrients and oxygen through the mother s blood supply and they also remove waste from the baby. Birth After about 9 months of growing and developing, the baby is ready to be born. The mother gives birth to the baby through the vagina. If there are any complications, the doctor might perform surgery called a Caesarean Section. A cut is made into the uterus through the mother s lower abdomen and the baby is removed. MENSTRUATION After ovulation, if the egg is not fertilised, it continues to travel down the fallopian tubes to the uterus. Instead of implanting into the lining, it will be discarded out of the vagina. The blood-rich lining of the uterus comes away and is also discarded from the vagina. This is called menstruation or a woman s period. This happens for about 4 7 days every month. It is a normal part of development and will continue every month for every woman until menopause. With the proper protection (sanitary pads and tampons) a girl/ woman can go about life as normal during this time of the month. MYTHS ABOUT MENSTRUATION AND SEX Myths are stories that are often passed down from generation to generation and are not based on facts or proof. There are many myths about menstruation and sex: Women who are menstruating are dirty. During your period, you should never eat cold food or walk bare-foot because if you get cold your period will be worse. You can t swim if you have your period. Virgins shouldn t use tampons because you can lose your virginity. You can t fall pregnant during your period. Women are always moody and irrational during menstruation.

5 Everyone is having sex. You can t get pregnant if it s your first time having sex. If you shower after having sex you won t get pregnant or catch an STD. Drinking and drugs make sex more fun. ACTIVITY Choose 5 of the above myths and research if they are true or false. Discuss your research with the class. WAYS TO PREVENT PREGNANCY AND STDs There are two risks for people who are sexually active (having sex): pregnancy and being infected with a Sexually Transmitted Disease (STD) like HIV/AIDS, Herpes, and Syphyllis. A Sexually Transmitted Disease is a disease that is spread or passed from one person to another person through sexual activity. Some STDs are treatable, but many are incurable (there is no cure for them) and are life-threatening (you could die from them). They often have lots of painful long-term symptoms. Contracting an STD can ruin your life and the lives of every person you might have intercourse with later on in life. Not cool! Having a baby is a massive responsibility. Not only do you have to go through 9 months of pregnancy, but after that, there is a baby that needs to be loved and looked after. Both the mother and father are responsible for the childs well being. There are different ways to prevent pregnancy and becoming infected with an STD. 1) Abstination/Abstinence The only way to guarantee that you will not get pregnant or make a girl pregnant or be infected with an STD is to not have intercourse. It s called abstinence abstaining from having sex. Wait until you are older and preferably for when you have someone you ve committed to love and care for and raise children with for the rest of your life. It s a wise choice to make to wait and it will save you a lot of concern regarding the risks of being sexually active. 2) Condoms Male condoms are rubber sheaths that are placed over a man s erect penis before intercourse. They prevent the sperm from entering the woman s vagina. Female condoms do the same thing, but they fit into the woman s vagina. They are much less commonly used. Condom s do prevent pregnancy and the spread of STDs, but they are not a 100% guarantee because they can break.

6 3) Oral contraceptive The pill CANNOT prevent the spread of STDs! It only prevents pregnancy. Most oral contraceptive pills prevent ovulation by giving a woman s body hormones. An egg is not released each month, but a woman still has her monthly period. A woman must take her pill at the same time every day and cannot miss any days otherwise it is not effective. They are not effective if the woman is sick or if she is taking antibiotics. 2 THINGS TO REMEMBER No matter what your choice is regarding having intercourse or abstinence... 1 NO ONE, no matter who they are, has the right to force you or persuade you to have sex with them! You have the right to say No. You get to decide when you have intercourse and who you have it with and no one is allowed to tell you otherwise! It s your choice! 2 Make wise choices and be responsible. When choosing a partner, make wise choices. Be responsible and protect yourself from an unwanted pregnancy and from becoming infected with STDs.

7 Answer sheet ACTIVITY Choose 5 of the above myths and research if they are true or false. Discuss your research with the class. Women who are menstruating are dirty. (It must be stressed that this myth is not true. In some religious beliefs women who are menstruating are called unclean but this is from a spiritual perspective please be sensitive to this. However, children should not be permitted to call a girl dirty because she is having her period. Girls should be encouraged to use good protection (tampons and sanitary pads) and change them regularly.) During your period you should never eat cold food or walk bare-foot because if you get cold your period will be worse. (This is not true because the uterus is the organ that controls menstruation, so having cold feet or eating cold food has no influence on it. If a girls is experiencing period pain during her period, it may help her to put a warm hotwater-bottle over her tummy to help sooth the pain.) You can t swim if you have your period. (You can swim if you have your period but you must use the right protection tampons. There s no reason why a girl shouldn t swim if she has the right protection. Exercise is good for soothing period pain as well.) Virgins shouldn t use tampons because you can lose your virginity. (Viriginty is about whether someone has or hasn t had sexual intercourse. Long ago, a woman s virginity was assessed by whether her hymen was in tact or not, as this breaks during sexual intercourse. However, this is not really done today. There are many reasons a girl s hymen can break throughout her life horseriding, gymnastics, and using tampons. However, this doesn t mean she has lost her virginity! ) You can t fall pregnant during your period. (There is a chance that you can fall pregnant if you ve had sex during your period. Sperm can stay alive inside the vagina and fallopian tubes for several days. There is a chance that after your period you could be ovulating and this means that you could fall pregnant.)

8 Answer sheet Women are always moody and irrational during menstruation. (This is not true. Most women (not all) experience different PMS (pre-menstrual syndrome) symptoms because of changes in hormone levels just before their period. A woman s mood or emotional state should not automatically be attributed to her PMS symptoms. Note that teenage boys can be equally moody and emotional.) Everyone is having sex. This is definitely not true. Unfortunately, many people think that it is and so they either become sexually active to become part of the cool kids or they lie and exaggerate about being sexually active. When you are young, other people s opinions about you seem so important. But remember, this is sex we re talking about, not your hairstyle or the sport you play! Deciding when you will become sexually active is a choice only you can make and should not be based on what your friends or the cool kids think! There is NO PRESSURE when it comes to making this decision if you feel like there IS pressure, then get out of that situation and think clearly. You can t get pregnant if it s your first time having sex. (This is not true. If a girl has started menstruating, then she has started ovulating. This means that you can fall pregnant. Remember that ovulation is when a girl s body produces an egg and there s no reason why that egg can t be fertilised by sperm and result in pregnancy.) If you shower after having sex you won t get pregnant or catch and STD. (Sex is an internal process for humans. Showering after having sex does not wash off the sperm or the fluids containing STD viruses. If the sperm have entered the vagina there is a high risk of pregnancy and contracting an STD.) Drinking and drugs make sex more fun. (If you are drunk or on drugs, you cannot make good decisions because these affect the parts of your brain that make decisions. Many people do things they wouldn t otherwise have done. Making decisions about sex are HUGE! They re not the type of decisions you want to make when you can t think clearly about them. It s a lie that having alcohol and drugs make sex more fun they actually impede the systems that make it more pleasurable.)