A lot of people wish we knew the whole answer to
your question, but no one does. Here is some of
what we do know. Your body is made up of
trillions of cells (a trillion is
1,000,000,000,000). These cells are so small that
you need a microscope to see them. In order for
us to grow, these cells have to divide. A cell
divides into two new cells. Each of these new
cells is just like their "mother cell" except for
being smaller. Then they grow and divide. Growth
hormone is a chemical that your brain makes to
tell other parts of your body to grow.
pretty easy for things like skin to get bigger,
but things are more complicated in other parts of
Bones have to be strong and
have a certain shape to do their jobs. (Try to
get a bone from a chicken drumstick and take a
look at it.) The long middle part is one piece.
There are also two end pieces. I'm not talking
about the softer white stuff on the very ends.
That is cartilage. In an adult chicken or person,
these three pieces have fused together into one
piece. In a growing person or chicken, they are
separate and the place where they meet is softer,
like the cartilage caps on the ends of the bone.
This is the growth plate. Cells divide here to
make the bones longer. As children start to turn
into adults, this plate fills in with bone and the
bones can't get any longer, so a person stops
getting taller. It happens sooner in girls than
in boys, so this is one reason men tend to be
taller than women.
Some cells don't
divide. Brain and other nerve cells hardly divide
at all after you are born. Brain cells can make
new connections, but you get almost never get new
ones. That's why babies have such big heads
compared to the size of their
Muscle cells can get bigger if you
use them, and smaller if you don't, but you don't
get new ones. Your heart is made of muscle.
If we knew how to get cells to divide
whenever we wanted them to, we could fix all kinds
of injuries. Unfortunately, the signal to stop
dividing seems to be in the DNA of each cell and
we don't know how to safely re-start the dividing.
When cells divide out of control, that's cancer,
which is very dangerous. So we have to be very
careful about trying to make cells divide after
If an adult takes growth
hormone, it will make the flat bones in their face
and hands get wider, but it will not make them any
taller. Can you figure out why?Thanks for asking.
A simple answer to this question is cell division.
When we are still growing the cells in our body
multiply in response to cellular and chemical
signals. These signals are carefully controlled
throughout our lives, especially when we are only
weeks old. For example, when you grow arms in the
womb cells divide an EXACT number of times and
then all stop at the same point. If every cell in
your new arms divided one time too many, your arm
would reach your toes while you were standing up!
A person's body is composed of cells, and cells
divide to make more cells. Cells are induced to
multiply by the circulation of growth hormones in
the body, and the expression of genes that induce
growth and multiplication. The exact mechanism by
which the control occurs is still being worked on.
Click Here to return to the search form.