Your body’s climate control system

While much of the nation is sweltering in the intense summer heat, have you ever wondered how we humans and other animals stay cool when it’s so hot outside?

The simple answer is sweating for humans. But do you know why sweating is an effective way to cool the body?


What do you want to know

  • Thermoregulation is the way we maintain body temperature with tightly controlled self-regulation regardless of outside temperatures
  • Humans have 2 million sweat glands that produce sweat
  • Evaporation helps cool body temperature
  • Humans could also cool their bodies through convection and conduction

Before we get into the science of how we cool ourselves, let’s look at what happens when our body’s air conditioning system kicks in. To survive, the body controls its own temperature, a process called “thermoregulation”. For humans, the maintained temperature is around 98.6 degrees, plus or minus a degree or two.

If you’re out long enough, especially on a hot day when you’re exercising, you sweat or sweat. This is when your body overheats and needs to cool down.

Have you noticed that when you sweat and the wind blows, it cools you down? That’s because the air moving against your damp skin helps evaporate sweat and cool you down. This is why fans are efficient.

Your body has over 2 million sweat glands that produce sweat on the surface of the skin. By using evaporation, your body can lower its temperature relatively quickly.

Here’s how it works. The moisture in your skin is in a liquid state. When it evaporates into the surrounding air, it turns into a gas.

This change of state, called evaporation, draws latent (hidden) heat away from the body, cooling the skin. Think about when you shower (especially in colder months) and when you go out. You feel chilly.

This is because the water on your skin evaporates, making you feel cold. The first thing you do is grab a towel to dry yourself off and stop the evaporation process.

As mentioned, evaporation is effective in cooling your body temperature. However, when the air is warm and humid or already contains a lot of water vapour, sweat has a much harder time evaporating. Therefore, you feel so uncomfortable on hot and humid days.

The sweat eventually doesn’t evaporate, but it rolls off your body and soaks into your clothes. This is also why hot, humid days can be dangerous because your body’s built-in air conditioning system may not be cooling down.

Body temperature eventually gets too high, which can lead to heatstroke and, in extreme cases, death.

Under the stress of keeping your temperature cool, your body can lose a lot of water when sweating for long periods of time. It is therefore important to replenish this water by staying hydrated.

On a related note, other animals have also used evaporation to cool themselves. Dogs, for example, do not have sweat glands. So, to take advantage of evaporative cooling, they use their tongues while panting.

By moving air over their moist tongue, the evaporation cools the surrounding air, which cools their nose and lungs.

Your body has other ways to cool itself than sweating. Your body will also dilate blood vessels near the skin’s surface, increasing blood flow. Through a process called “convection”, we transfer body heat to the surrounding air.

Another process called “conduction” occurs when your body cools itself by transferring some of its own heat to another cooler surface. So the next time on a hot summer night, you’ll feel compelled to flip the pillow to the cooler side…that’s the reason.

So remember, help your body by giving it a few breaks by going indoors to allow it to cool down. Drink plenty of water to replenish water lost through sweating.

Also, listen to your body. If you feel dizzy, have a stomach ache, or have a headache, these are signs that your body is losing the battle to stay cool. Go to a cooler place and drink water.

Also, remember to watch the elderly, as older bodies have a harder time staying cool.

Also, don’t forget our four-legged friends. They deserve a cool place to stay and plenty of water like us.