We all know that you sweat in order to attempt to lose heat and reduce the temperature of the body. But why is it the chosen method for humans? And how does it work?

The human skin surface area is very large. In fact, if all the skin cells of the body were lined up next to each other they would reach around the circumference of the earth. No wonder we spend so much on skincare. Add to this the fact that the surface of the skin is largely bald, and you have one very large, flat heat exchange area that is brilliantly adapted to losing heat quickly, although it can be restricted by beauty products on the skin. Dogs do not have sweat glands the same as us and even if they did they would not lose heat efficiently from the skin surface as it is covered in hair. They instead pant, using the largest and most flat area of tissue to to lose heat, that being the tongue.

Heat is actually taken away from the surface of the skin when a human sweats by a process known as evaporation. Now water evaporates all the time from everywhere. Puddles, clothes, the ocean…they are all subject to evaporation, but what most people don’t realise is that when the water gets taken up into the atmosphere, heat is taken with it. This is because turning water into a gas requires energy. When the water is lying on the skin surface, it takes energy in the form of heat from the body and turns into a gas, and puff, it’s gone. Water is used readily by the body as it is made up of around 75% of the stuff. This is why sweating is often our preferred method of heat loss but as you can imagine causes problems when our resources are depleted as all our organs also need water to function. Although a fast an effective way to lose heat, humans struggle to survive in very hot and dry places, and this why using sweating is not an option for desert animals.

 

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