Human reproduction is sexual, with internal
fertilization and viviparous
development of the zygote and embryo.
The male
reproductive system
is formed of:
The penis:
a long cylindrical organ, covered in skin. Inside runs the urethra (a part of
both the reproductive system and the excretory system).
The testicles:
are the size of a nut. They produce sperm.
The scrotum:
The sack of skin that covers the testicles.
The vas
deferens: A tube that connects testicles to the urethra.
The glands:
prostate and seminal vesicles. They
produce liquids that mix with the sperm and form semen.
The female
reproductive system
is formed of:
The ovaries:
Two oval organs, the size of a nut. They produce ovules.
The fallopian
tubes: Two tubes that connect ovaries and uterus.
Uterus: An organ made of muscle. It shape and size is a
pear.
The vagina:
A tube that connect the female reproductive system to the exterior.
Vulva: Formed by folds of skin, called labia.
Fertilization is the union of a sperm and a mature
ovule, which produces a zygote.
Pregnancy is the period when the zygote becomes the embryo, and
the embryo develops inside the mother’s uterus.
Childbirth is when the baby leaves the mother’s body.
Fertilization happens in the fallopian tube. The zygote
that forms becomes the embryo. This enters the uterus and
becomes joined to the wall. In this way the pregnancy starts.
Pregnancy lasts about nine months and is divided in three phases of three months each
one: first trimester, second trimester and third trimester.
When the baby is ready, the muscles of the wall of the
uterus produce contractions. The
amnion breaks and the baby comes out of the vagina.
The umbilical cord is cut. The remains of the cord
leave a scar on the abdomen of the baby: the
navel.
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