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