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Weird Science: We Are Water

NGSS Crosscutting Concepts
Table of Contents


SF Fig. 1.5. You are mostly water.

Image by Alyssa Gundersen

Over half of human blood is made up of water (SF Fig. 1.5)! About three-quarters of our body is made up of water. Water regulates body temperature, maintains our muscles, lubricates joints, prevents constipation, flushes out waste products, carries nutrients to our cells, and protects our organs and tissues. We cannot function without water. Just being 2 percent dehydrated can degrade physical and mental functions, for example, making it difficult to focus on this paragraph. At a 4 percent loss of water, your capacity for muscular work decreases; a 6 percent loss can cause heat exhaustion; just an 8 percent loss of water can cause hallucinations. A lack of water is a major cause of daytime fatigue. You can assess if you are getting enough fluids throughout the day to stay hydrated by using a simple urine color chart (Fig. SF. 1.6).



SF Fig. 1.6.  On this hydration urine color chart, the color of your urine should be clear or light yellow and match the colors in categories 1, 2, or 3. These categories indicate you are hydrated. This chart may not be accurate if you are taking vitamin supplements or some kinds of antibiotics.

Image by Brittany Supnet

Making the right choices in your diet can help you stay hydrated. This includes drinking not only water, but also other fluids like juice. Some foods, like leafy greens, melons, and tomatoes, contain a lot of water. Some liquids, on the other hand, are not good for staying hydrated. Beverages with caffeine, like coffee, tea, or soda, have a natural diuretic effect, meaning they make your body urinate more, getting rid of fluid. Some foods, like onion, eggplant, and asparagus, may also have a diuretic effect. Our bodies lose water through sweating, urinating, and even breathing, so make sure to stay hydrated by making drinking plenty of water and eating the right foods.

Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.