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What is reproduction?. Reproduction is one of the seven life processes. All living things reproduce. Humans use sexual reproduction to produce their young. In order to do this, the two parents (male and female) have different reproductive systems and organs that produce different sex cells.
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What is reproduction? Reproduction is one of the seven life processes. All living things reproduce. Humans use sexual reproduction to produce their young. In order to do this, the two parents (male and female) have different reproductive systems and organs that produce different sex cells.
Sex cells – sperm In males, the sex cells are called sperm. tail middle piece head nucleus containing DNA cell membrane Sperm are produced in sex organs called testes.
Sex cells – egg In females, the sex cells are called eggs. nucleus containing DNA cytoplasm membrane jelly coat Eggs are produced in sex organs called ovaries.
What is fertilization? For a woman to become pregnant fertilization must occur. Fertilization is the fusing of an egg and a sperm cell. In this process the sperm’s nucleus will join with the egg’s nucleus. Females produce an egg approximately every 28 days. This is calledovulation. Males continually produce sperm in the testes. How do these cells come into close contact with each other?
Sexual intercourse During sexual intercourse the man inserts his penis into the woman’s vagina. Millions of sperm cells are ejaculated into the top of the vagina. They enter the uterus through the cervix, where the sperm cells may meet an egg. Now fertilization can occur.
What are contraceptives? Contraceptivesare devices designed to prevent pregnancy. Some types of contraception can also stop the spread of sexually transmitted infections. Sexually transmitted infections are diseases that can be passed on by sexual contact. Contraceptives are not 100% reliable and some can cause other side effects. How do the different types of contraceptives work?
Different types of contraceptives • Condoms– a latex barrier worn over an erect penis. This barrier prevents sperm entering the vagina and causing pregnancy. It can also help to stop the spread of sexually transmitted infections. • Contraceptive pill – a pill containing a mixture of hormones taken every day. These hormones stop the release of eggs, preventing pregnancy. However the pill cannot protect against disease. • Diaphragm and cap – these are barriers inserted into the vagina to prevent sperm reaching the egg.
Alternatives to contraception Some people in long term relationships choose to use natural family planning instead of contraceptives. This involves working out when the woman is fertile and avoiding sexual intercourse at these times. This method does not have any effect on the body, but it can be an unreliable form of birth control and does not protect against sexually transmitted infections.
Emergency contraception Emergency contraception is available to women that have had unprotected sex, to prevent pregnancy. This is in the form of a pill, often called the ‘morning after pill’. It should be taken within 3 days of unprotected sex, in order to be effective. However, it does not protect against sexually transmitted diseases and it can have side effects.
The placenta How does an embryo receive food and oxygen and how does it get rid of waste? An embryo forms a structure called the placenta, which attaches to the uterus wall. umbilical cord The umbilical cord joins the fetus to the placenta. In the placenta, food and oxygen diffuse from the mother’s blood into the blood of the fetus. Carbon dioxide and waste products diffuse from the blood of the fetus into the mother’s blood.
From embryo to fetus In the earliest stages of development, a human baby is called an embryo. After the first eight weeks of pregnancy, a human embryo is then called a fetus. At this stage, the fetus has all the main human features. The fetus continues to develop and grow inside its mother’s uterus for a total of 40 weeks.
Birth After 40 weeks of gestation, the baby is ready to be born. At this point, the head usually lies just above the cervix. Birth begins with small contractions of the uterus wall, which gradually become stronger and more frequent. Eventually the contractions cause the amnion to break and the fluid escapes. The cervix then widens and dilates as the baby is pushed through the vagina. After a few minutes, the placenta comes away from the uterus wall. This is pushed out as the afterbirth.
What happens during puberty? Humans are born with a complete set of sex organs. However, they do not usually become active until between the ages of 10 and 18. In males, the testes start to make sperm, and in females, the ovaries start to release eggs. This stage of development is calledpuberty,and is caused by hormones. During this important time, many changes take place in the bodies of young men and women.
Menstruation An important part of puberty for girls is the beginning of their monthly cycle. This is known as the menstrual cycle. The menstrual cycle involves the preparation of the uterus lining so that it can receive a fertilized egg. If an egg is fertilized, it can implant itself in the prepared uterus lining. If the egg is not fertilized, the lining of the uterus breaks down and is lost from the body. This is called menstruation,or a period.
