What is Sweat? - Definition & Function

Lesson Transcript
Instructor: John Williams
Sweat is a fluid excreted by the body to help maintain normal body temperature. Learn about homeostasis, the definition and function of sweat, how sweat cools the body, and the disorder associated when the body does not produce sweat. Updated: 10/03/2021


Homeostasis is the process by which the body maintains a stable internal environment. This internal environment is composed of many factors, including pH, energy production, and temperature. Our body temperature is, on average, around 98.6 degrees Fahrenheit. If our body temperature moves above or below that temperature too much, our bodies will try to correct that change. One of the primary ways that the body is able to lower temperature in the event that it gets too high is by releasing sweat.

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  • 0:00 Homeostasis
  • 0:31 What Is Sweat?
  • 1:19 How Does Sweat Cool The Body?
  • 2:13 What If You Don't Sweat?
  • 2:54 Lesson Summary
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What Is Sweat?

You're likely familiar with what sweat looks and feels like. But do you know of what, exactly, it's composed? Sweat is a fluid that's released from the body's skin. When the body gets too hot, the nervous system will stimulate the glands of the skin to start producing this fluid, which is used to cool the body and bring its temperature down. Sweat is composed of several components:

  • Water, which is the primary component, and makes up 99% of sweat
  • Salts, which are released as part of the excretory, waste removal function of the skin
  • Urea, which is another waste product

Incidentally, these same components are found in urine, which is produced by the kidneys. Yes, urine and sweat essentially contain the same chemicals, but in different concentrations. Therefore, both of these organs are responsible for waste homeostasis.

How Does Sweat Cool the Body?

Think about the times that you can remember sweating. I would guess that the most obvious times were those where the temperature around you was high or when you were performing some type of exercise or activity.

High temperatures outside of the body will initially cause the body temperature to change. Likewise, muscular activity will produce heat as energy is burned, causing internal body temperature change. In both cases, heat is being applied or produced around the body, and this can increase the body temperature outside of the normal range.

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