Water, gases, and solids enter and leave the human body through various means. F
ID: 942160 • Letter: W
Question
Water, gases, and solids enter and leave the human body through various means. For an "average" human over the course of a day, these masses arc shown in the figure below Verify that the total mass entering the system equals the total mass leaving the system (b) Some of the solids arc "burnt" to yield energy, CO_2 and water. How much water is generated within the body If the external temperature rises, and the body looses thrice the amount that it previously did through sweat, how much more water will the person have to drink to maintain the same body mass (assume that the water gained lost through other means remain unchanged).Explanation / Answer
a) Mass entering the system = 432 g + 1000 g + 1200 g + 515 g + 50 g = 3197 g
Mass leaving the system = 350 g + 565 g + 200 g + 1400 g +70 g + 200 g + 12 g + 400 g = 3197 g
b) Approximately 250 mL of water is generated per day from cellular metabolism.
c) The body is about 60% water, give or take. We’re constantly losing water from our bodies, primarily via urine and sweat. There are many different opinions on how much water we should be drinking every day. The health authorities commonly recommend eight 8-ounce glasses, which equals about 2 liters, or half a gallon. There are studies showing heat can cause mild dehydration (1-3% of the body weight). However, keep in mind that just 1% of body weight is actually a fairly significant amount. This happens primarily when you’re sweating a lot, such as during exercise or high heat. So, one person should drink approximately 1% of the body weight in water (remember density of water is 1g/mL).
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