Certainglands in the lower layersofthe skinextractthese wastes from
the blood. These are the sweat glands which collect wasteproductsand send
them to the surfaceofthe skinthroughlong tubes. The pores on the surface
ofyourskin are the openingsofthe tubes, orducts,ofthe sweat glands.
THE SKIN- ABUILT-IN THERMOSTAT
Materials:Cold water,rubbingalcohol, absorbentcotton.
Follow this procedure: Wet a pieceofabsorbentcotton with water and
sponge the insideofyour left wrist with it. How does your wrist feel as the
waterdries?
Immediatelyafter, sponge your right wrist withanotherpieceofabsorbent
cottonsoaked inrubbingalcohol. How does your wrist feel after thealcohol
hasdried?
Which liquid dries morerapidly?
You will observe:Thealcoholwill dry morerapidlythanthe water.
Yourleft wrist will feel cool as thewaterdries, but your right wrist will
feel even cooler.
As water evaporates(dries) from the surface ofthe skin, it removes a
certainamountofbody heat. Since alcohol evaporatesfaster thanwater, it
cools the body fasterthandoes water.
Yourskin is a built-inthermostat. Asperspiration,or sweat,evaporates
from your skin some bodyheatis driven off,makingthe body generally cooler.
Therefore,it is to youradvantagetoperspirein the summer.
Since bathingthe skin with alcohol hastens the lossofheat, doctors
recommendalcoholbathswhen apersonis ill and has a high fever. Analcohol
bathwill lower a"fever"somewhat. A hightemperaturecauses theheartto