People loose moisture through evaporation from the pores in the skin. When you
are hot and begin to sweat, your rate of respiration speeds up in an effort to cool your
body. Skin moisture can evaporate rapidly in dry climate, even when you are not sweating.
On average, an adult loses about one liter of water a day. When working hard and burning
energy that produces heat, that persons water loss quickens proportionally.
Create a lab that
demonstrates aspects of water loss from your body.
- one plastic bag or plastic
wrap per student
- masking tape
- paper and pencil
Cut the plastic bag into a single layered square large enough to fit comfortably around
your forearm and tape it securely (but not too tightly) at the top and bottom.
Wear the plastic over your forearm for at least ten minutes. Meanwhile, in teams of four
people take and record your pulse and respiration rates. Then walk up and down a flight of
stairs five times. Record your new pulse and respiration rates. Next, run up and down the
stairs five times and then record pulse and respiration.
After the exercise note whether the plastic contains any water condensation released by
your skin as it performed respiration and perspiration.
4. Take the bag off and feel the moisture on your
skin where the plastic has been. Note the moisture level of the skin that was under the
plastic as compared to skin exposed to air during the ten minutes.