The Water In You
Think of what you need to survive, really just survive. Food? Water? Air? Naturally,
I'm going to concentrate on water here. Water is of major importance to all living things;
in some organisms, up to 90 percent of their body weight comes from water. Up to 60 percent
of the human body is water, the brain is composed of 70 percent water, blood is 82 percent
water, and the lungs are nearly 90 percent water.
There just wouldn't be any you, me, or Fido the dog without the
existence of an ample supply of water on Earth. The unique qualities
and properties of water are what make it so important and basic
to life. The cells in our 
bodies are full of water. The excellent ability of water to dissolve
so many substances allows our cells to use valuable nutrients, minerals,
and chemicals in biological processes. Water's "stickiness" (from
surface tension) plays a part in our body's ability to transport
these elements all through ourselves. The carbohydrates and proteins
that our bodies use as food are metabolised and transported by water
in the bloodstream. No less important is the ability of water to
transport waste material out of our bodies.
For more information, please go see http://ga.water.usgs.gov/edu/propertyyou.html
