The Role of Water in Human Biology

The Role of Water in Human Biology
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  • 0:03 What Exactly Is Water?
  • 1:03 Water in Human Biology
  • 1:35 Cell Life & Transport
  • 2:07 Chemical Reactions
  • 2:30 Body Temperature &…
  • 3:14 Lesson Summary
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Lesson Transcript
Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

After completing this lesson, you will be able to explain why water is so important, and describe the five main functions of water in the human body. A short quiz will follow.

What Exactly Is Water?

Water is the most important natural resource in the world. Without it, we humans wouldn't exist. Not only can we not go more than a few days without water, but life on Earth most likely would never have evolved at all. And then there are all the more trivial uses: cooking, bathing, washing clothes, brushing teeth, flushing toilets, and watering plants. Humans use a lot of water.

Water is a compound containing molecules, each of which is made up of two atoms of hydrogen and one atom of oxygen bonded together. Across a large proportion of the Earth it's in liquid form, which is convenient because humans need to drink it. Though at the poles it is a solid called ice, it can also evaporate to form water vapor. Water vapor then rises to create clouds, which eventually cause rain. On Earth, water literally falls from the skies. This little fact is something we're so used to that it may seem trivial, but it's a pretty big deal.

Water in Human Biology

Water is vital to human biology, and indeed, all biology on Earth. We currently believe that the presence of liquid water is an important requirement for the development of life, to the point that it's the main thing we're searching for in our attempts to find life elsewhere in the solar system.

But why exactly is water important to human biology? There are five main functions of water in the human body:

  • Cell life
  • Transport
  • Chemical reactions
  • Temperature regulation
  • Waste excretion

Cell life is based on the fact that cells have water inside them. Water is used to transport nutrients to cells and within cells (intracellular). If cells don't get nutrients including vitamins, minerals, and sugars, they die.

As mentioned, water is needed for transport. It's how oxygen and food make it through our bodies, and how blood flows through the veins and arteries to take those nutrients to where they're needed. Blood is, after all, 92% water. In fact, 60% of your entire body is water!

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