transcript: Every living organism we know of requires
water to survive - it's part of the reason we look so feverishly for water on other planets
across the universe, and consume it consistently every day here on Earth. So what would happen
to your body if you stopped drinking water? Of course, when we say 'water' we're including
all fluids which simply contain water - like juices, pop, or tea. Much like the desire
to breath in oxygen, thirst is a survival instinct. H20 is the most abundant molecule
in the human body making up, on average, 65% of an adult. As a universal solvent, it carries
nutrients and hormones through the body, regulates body temperature, cushions our joints and
even lubricates our eyes. You produce around 1.5 litres of urine every day, with another
litre lost from breathing, sweating and...pooping. So it's essential that the body replaces this
liquid. The thirst centre of the brain is located
in the hypothalamus, and is constantly using sensors in your blood vessels to monitor the
amount of sodium and other substances in your body. For example, if you sweat too much,
your blood volume and pressure fall. The brain then detects this change and creates the urge
to drink something, NOW! So what happens if you are unable to satisfy this thirst? The initial signs of dehydration are the obvious
dry mouth, following which your urine becomes darker with a stronger odor, as your body
attempts to conserve more fluids. The lack of H20 then begins to affect your brain - you
may feel light headed, have a slower response time and decreased ability to feel pain. In
fact, when you're dehydrated, your brain tissue literally shrinks. In studies observing hydrated
vs. dehydrated participants, the same task required more brain power and oxygen in dehydrated
individuals compared to those fully hydrated. After a day or two with no fluids you'll stop
peeing all together, have trouble swallowing, suffer from muscle spasms and likely experience
nausea - after all, your body can survive without food much longer, and attention to
digestion is not a priority at this point. Eventually, victims may become delirious with
severely impaired brain function. Interestingly, studies looking at elderly patients who suffer
from delirium, found that many are simply suffering from chronic dehydration in the
first place. After even more time without water, the blood stops flowing to your skin,
reducing heat loss but increasing your core body temperature. This can lead to a grey-blueish
tinge to your skin. Beyond 3-5 days without water, and your body will begin to shut down
it's organs, and eventually the brain. Of course, unlike the plentiful oxygen we
breath, only 2.5% of all Earth's water is fresh; most of which is locked up in glaciers,
ice caps and underground lakes known as aquifers, leaving less than 1% available for drinking.
And most of this water is actually used to grow crops; approximately 500 billion litres
of freshwater is used daily for agriculture in the USA alone, with another 500 billion
litres to cool electric power plants. And as our personal drinking sources become increasingly
contaminated, over 783 million people on earth are unable to access clean water. Scientists around the world are trying to
find solutions to this problem - from attempts to remove salt from ocean water, tap into
underground aquifers and creating innovative water filtration systems. If we look to space,
NASA has developed technology for astronauts to turn their urine into water more pure than
what we drink on earth. But we can't just rely on science and technology - perhaps the
solution relies on us as a species to understand and contribute to this global water crisis. If you want to help in the mission to end
global thirst, join in World Water Day on March 22nd. There are a lot of really amazing
projects out there, like Water.org or even the awesome UNICEF app which donates 1 day
of clean water to child in need, for every 10 minutes you put your phone down. We'll
leave links in the description for these and other great water charities. Small investments
really do make a huge difference. We'll be donating all the proceeds from this
video to a water project close to us called Morocco 5 Villages - so thanks for supporting
and watching. And subscribe for more weekly science videos!
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