<span>The respiratory system is made up of several organs and structures, including the lungs, windpipe, diaphragm and alveoli. It is responsible for taking in oxygen and expelling carbon-dioxide waste.Here are 11 surprising facts about the respiratory system.
</span>You lose a lot of water just by breathing.
Breathing allows you to take in the oxygen your cells need and expel carbon-dioxide waste. But when you exhale, you also breathe out a lot of water.
How much water do you lose from breathing?
When at rest, humans exhale up to 17.5 milliliters (0.59 fluid ounces) of water per hour, according to a 2012 article in the journal Polish Pneumonology and Allergology. But you lose about four times that amount when you exercise, the study said.
Some people can hold their breath for more than 20 minutes.
The average time an adult can hold his or her breath is between 30 and 60 seconds. This limitation has more to do with the buildup of blood-acidifying carbon dioxide than the lack of oxygen, which your body stores in muscle proteins called myoglobin.
But free divers — people who practice the sport of diving underwater without using equipment like scuba gear — have different techniques, such as hyperventilation, to decrease the concentration of carbon dioxide in the blood, allowing them to hold their breath for remarkably long times. Denmark's Stig Severinsen currently holds the Guinness World Record for the longest free dive — in 2010, he held his breath underwater for 22 minutes.
