Here at Seeker World Headquarters, actually an underground bunker complex in western Nevada, we know only one kind of thirst: The thirst for knowledge! Also, occasionally, Vernors -- Detroit's high-octane contribution to the world of ginger ale.
The sensation of thirst is critical to the survival of pretty much every animal species, and yet the specific mechanics of the phenomenon have eluded science for years. Happily, new research published in the journal Nature has changed all that. Jules Suzdaltsev reports in today's DNews dispatch.
Some background: Water is the single most important nutrient for animals -- and yes, it's a nutrient, technically speaking. We humans are made up of about 60 percent water, and maintaining proper hydration is one of the major functions of the brain.
The sensation of thirst, therefore, is your brain's way of trying to adjust unbalanced fluid levels in the body. When the brain detects that your blood is too salty, it generates a thirst response in hopes that you will adjust your behavior accordingly to seek out water.
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The weird thing that's puzzled scientists is that, when you drink water, the sensation of thirst is more or less immediately dispelled. Compare this to hunger, which usually doesn't abate until 20 minutes or so after you eat.
The new research published in Nature, from the University of California, may have solved the mystery. It seems that a particular area of the brain, called the subfornical organ, reacts immediately to oral stimulation -- the very act of drinking and swallowing.
What's more, neurons within the subfornical organ are actually able to predict your future fluid levels based on your current blood composition and how much water or food is in your mouth. When they think you've had enough, they stop firing and you stop feeling thirsty.
These so-called thirst neurons are a significant discovery in that they parse data from a number of different sources -- the mouth, the brain, the blood -- then automatically make predictions based on that information.
Check out Jules' video here for more details, or click on over to Trace Dominguez' unsettling report on what actually happens to your body when it gets dehydrated. Both feature dry humor.
-- Glenn McDonald
Nature: Thirst Neurons Anticipate The Homeostatic Consequences Of Eating And Drinking
USGS: The Water In You
BBC: Brain's Thirst Circuit 'Monitors The Mouth'