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REPRODUCTION (Human reproduction involves two different sex cells: a…
REPRODUCTION
Human reproduction involves two different sex cells: a female ovum and a male sperm. Each cell carries different genetic information which is why children are unique.
BIRTH:When the foetus is ready to born ,it pushes against the cérvix wich starts to open and widen.The muscles of the uterus begin to contract and the cérvix open sufficiently to allow the foetus, now a baby to pass.
FERTILISATION:During sexual intercourse the penis is inserted to the vagina and the sperm are deposite there.Then the sperm start to swim up of the vagina and only onesperm can fertilisean ovum.Once the ovum fertilished the cells divide and mutiply, this called zygote.
DEVELOPMENT OF THE EMBRYO: After fertilisation, the zygote travels to the uterus where its cells carry on dividing and multiplying they became an embryo .
DEVELOPMENT OF THE FOETUS: After about nine weeks, all the organs have formed and the embryo develops into a foetus. The foetus floats in a sac of amniotic fluid. The foetus recives oxygen and nourishment from the the mother's placenta. The baby is connected to the placenta by the umbilical cord.
Puberty in girls: when girls approach sexual maturity, their bodies undergo a series of changes. They grow taller and their body fills glands in the skin. Arpit hair begins to grow and mentruation typically starts between 10 and 15 years.
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The menstrual cycle: once a girl reach puberty the ovaries, in responset hormons realased by the brain start to relase ova. An ovum is realased from the ovaries into one of the fallopian tubes about every 28 days.This process is called ovulation the walls of the uterus get thicker with extra blood.
Menstruation tipically last from 3 to 5 days. Woman menstruate until they have no eggs left. This usually happens when a woman is about 50. This period is called the menopause.
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Puberty in boys: when boys reach puberty the brain secrets hormons wich activates the testicles to produce testosterone. This hormons brings about many physical changes. Secondly public hair begins to grow , the skin becomes coarse .
Sperm: the male reproductive system produces and transpotrs sperm cells. The sperm has an oval shape and a tail, the tail allows ich to move up fallopian and fertilise the ovum. Men produce millions of sperm every day.
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