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Unit 4Human Reproduction
Reproduction is a live process that lets living thingscreate other living things that are similar to them.Humans beings reproduce though sexual reproductionbecause their reproduction unites male and female sexcells. Humans are viviparous mammals.
REPRODUCTION
Both the male and female reproductive cells are made in the male and female reproductive systems respectively.
Reproductive systems are already formed at birth and tell us if the newborn is a boy or a girl. The different traits of each reproductive system are called primary sexual features.
PRIMARY SEXUAL FEATURES
Between eleven and fifteen years of age, reproductivesystems mature. This stage is called puberty. There aresome physical changes that are the same to both sexes, like growing hair in the armpit and pubic areas.There are other changes that are specific for each sex:Gils develop breast and their hips get wider.Boys get deeper voices, they get facial hair and theirshoulders get wider.These external features that are differentiate men fromwomen are called secondary sexual features.
SECONDARY SEXUAL FEATURES
Reproductive cells or sex cells are responsibility for carrying out
the function of reproduction. There are two types:
Ovules. They are the female reproductive cells. They are big and
round. They are immobile. An ovule matures every month since
puberty.
Sperm. They are the male reproductive cells. They are small.
They have a head and a long tail called flagellum that helps
them to move. They are constantly produced since puberty.
REPRODUCTIVE SEX CELLS
Most of the female reproductive system is inside the abdomen.
The organs of the female reproductive systems are:
Ovaries: They produce ovules.
Uterus: A foetus develops inside it.
Vagina: It is the canal that connects the uterus to the outside of the body.
Vulva: It is outer part of the female reproductive system. It is made up of folds of skin called labia that protect the entrance to the vagina.
Fallopian tubes: They connect the ovaries to the uterus. The ovule and sperm join inside during fertilisation.
FEMALE REPRODUCTIVE SYSTEM
Most of the male reproductive system is outside the body. It ismade up of different organs:Testicles: They are outside a male’s body. They produce sperm. They are covered by a
bag of skin called the scrotum.Vas deferens: They are two thin tubes that take the sperm from the testicles to the urethra.
They are inside the abdomen.Urethra: It is the tube that takes urine or sperm outside the body.Penis: It is outside the male reproductive system. The urethra is inside it.Seminal vesicles and prostate: They are glands that produce seminal fluid and send it
to the urethra
MALE REPRODUCTIVE SYSTEM
Fertilisation occurs when a sperm joins the ovule in one of thefallopian tubes. This union creates a single cell called zygote. Thefertilised zygote goes down the fallopian tubes to the uterus. At thismoment, the zygote is now called an embryo. Although an ovule isnot fertilised, it goes down to the uterus and continues to moveThrough the vagina along with a small amount of the blood. This iscalled a woman’s menstruation or period.
FERTILISATION
Pregancy lasts about nine months.There are some estructures that are created to protect thebaby:-The placenta. It takes nutrients from the mother’s blood
and give it to the baby so it can develop.-The umbilical cord. Connects the embryo to the placenta.-The amnnotic sac. It is a membrane filled with fluid that
protects the embryo.
THE DEVELOPMENT OF AN EMBRYO
The embryo has all its organs formed after the first threemonths. At this moment, we can call it a foetus.-By the fifth month the mother can feel the baby’smovements.-After nine months the baby is ready to be born.Premature babies are born early and often need
speciallycare.
THE DEVELOPMENT OF A FEATURE
Childbirth is when a baby leaves its mother’s womb.The childbirth has three stages:-LABOUR -BIRTH-AFTERBIRTH
CHILDBIRTH
This work has been made by Ainoa Álvarez Duran