- Welcome to the reproductive system. So, let's start by asking, "What is the reproductive system?" It's basically a system in
our bodies that includes our sex organs and certain
parts of our brain. You can see the sex
organs here on the male, and here in two places on the female. So, this system within our
bodies allows us to reproduce, it allows us to make babies. And to make babies what
we're doing is combining genetic material from a
biological mother's egg and a biological father's
sperm to make our offspring. And we typically do this
by sexual intercourse. So, let's first take a
brief look at a couple of the most important sex
organs that make males and females have in their
reproductive systems. So, the males have the testes. And these are the most
important structures. Sort of the structures
that everything else is built around in a male. And that's because the testes produce his contribution to a baby. They make these small mobile cells that carry his genetic
material into a female to fuse with her genetic
material to cause a pregnancy. And these small mobile
cells are his sperm. Another important male organ is the penis. And the penis is used to deliver his sperm inside the female mate to increase the chance
that it meets her egg. So, those are really
the major male organs. Now on the female side, one of her major organs is the ovary and she has two just like
how males have two testes. And in fact the ovaries
and testes are homologous, they came from the same
precursor in development. Now the ovaries are responsible
for producing the female's genetic contribution to
a baby, that is the egg. The ovaries, though, are a
lot different to the testes, in that the testes are
constantly producing lots and lots of sperm. To the tune of of millions per day. Where as the ovaries only
release one egg per month. So, the next really important female organ is called the uterus. And the uterus is basically
a really thick muscular organ that's capable of stretching out and it's actually where the
baby's actually developing during pregnancy until birth. The next really important female
structures are the breasts. And the breasts are important
because they produce milk during the pregnancy and afterwords via a process called lactation. And lactation happens due
to a series of hormones that generally get
released around pregnancy. So, this breast milk that
gets produced can feed and nourish the growing baby and it actually plays a roll in creating a stronger immune system for the baby. So, we've seen some of
the major structures of both male and female
reproductive systems. But is that all the
reproductive systems are? Actually, no. Besides producing the sperm and egg, the reproductive systems produce chemicals whose signals have a
really strong influence over activities in our bodies. We call these chemicals, hormones and because they come from
our reproductive systems we refer to them as our sex hormones. For example, the male's major
sex hormone, testosterone, which is actually produced in the testes, is responsible for many masculine traits. Such as body hair, the
deepening of your voice, muscle growth, and there's
possibly even a link to levels of aggression in males. On the female side of things,
the ovary is the primary producer of some major female hormones, like estrogen and progesterone. Estrogen and progesterone play
a major roll in the timing of egg release from the ovaries. Estrogen is also responsible
for the development of a lot of feminine traits. For example, breast development. So, there's the making
of the sperm and the egg, there's the production of
the major sex hormones. What else does the reproductive system do? Well it does one more
really important thing. And that's coordinate the
meeting of the sperm and the egg. And it does that by the males
penis and the females vagina. These two organs are used to ensure that the sperm and the
egg meet each other. So, the penis actually deposits
sperm within the vagina, so that sperm has a
better chance of reaching and fertilizing the egg released inside her reproductive tract. So, you might be thinking,
"Does the reproductive system "do all this stuff on it's own?" I mean what tells it what to do? And that's a good question. The reproductive system is
actually controlled by the brain. There's an area in the brain
called the hypothalamus that sits just about there
on the inside of the brain, just about in the middle. And the hypothalamus
actually releases a hormone called gonadotropin
releasing hormone or GNRH. GNRH effects another
part of the brain called, anteriorpituitary which
sits right about there just under the hypothalamus. And anteriorpituitary in
response to GNRH releases two hormones lutenizing hormone or LH and follicle stimulating hormone or FSH. And its the lutenizing hormone and the follicle stimulating hormone that primarily effect the
male and female sex organs. So, the male's testes
and the female's ovaries to control their functions. Finally, a word on pregnancy, as pregnancy is a huge
part of reproduction and certainly the most long lasting part. So, pregnancy results
when a sperm successfully fertilizes an egg to create a zygote. A zygote is a first cell in a new organism that has genetic material
from both mom and dad. And that genetic material
has come from the sperm and the egg that have fused. The zygote goes through
a series of developments and eventually implants
itself within the inner wall of a woman's uterus to grow. So, that's in here, remember that thick muscular
organ we talked about? The third step is what we'll
really broadly call gestation. Gestation is basically the development of the fetus into a baby. So, the development of all
the fetus's organ systems including their brains,
spinal cord, lungs, cardiovascular system,
their reproductive system, all the systems in their body. Gestation readies the
developing infant to be born. And it takes about nine months. When the babies ready to
come out of the uterus and into the world a number of hormonal changes take place in the mother's body. This signals her to start
getting ready to push the baby out of her body, in other words, give birth to the baby. She then goes through
a process called labor, also known as parturition,
to give birth to the baby. After the baby's born, the last step is to
give him or her a name.