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  • Water is virtually everywhere,

  • from soil moisture and ice caps,

  • to the cells inside our own bodies.

  • Depending on factors like location,

  • fat index,

  • age,

  • and sex,

  • the average human is between 55-60% water.

  • At birth, human babies are even wetter.

  • Being 75% water, they are swimmingly similar to fish.

  • But their water composition drops to 65% by their first birthday.

  • So what role does water play in our bodies,

  • and how much do we actually need to drink to stay healthy?

  • The H20 in our bodies works to cushion and lubricate joints,

  • regulate temperature,

  • and to nourish the brain and spinal cord.

  • Water isn't only in our blood.

  • An adult's brain and heart are almost three quarters water.

  • That's roughly equivalent to the amount of moisture in a banana.

  • Lungs are more similar to an apple at 83%.

  • And even seemingly dry human bones are 31% water.

  • If we are essentially made of water,

  • and surrounded by water,

  • why do we still need to drink so much?

  • Well, each day we lose two to three liters through our sweat,

  • urine,

  • and bowel movements,

  • and even just from breathing.

  • While these functions are essential to our survival,

  • we need to compensate for the fluid loss.

  • Maintaining a balanced water level is essential to avoid dehydration

  • or over-hydration,

  • both of which can have devastating effects on overall health.

  • At first detection of low water levels,

  • sensory receptors in the brain's hypothalamus

  • signal the release of antidiuretic hormone.

  • When it reached the kidneys, it creates aquaporins,

  • special channels that enable blood to absorb and retain more water,

  • leading to concentrated, dark urine.

  • Increased dehydration can cause notable drops in energy,

  • mood,

  • skin moisture,

  • and blood pressure,

  • as well as signs of cognitive impairment.

  • A dehydrated brain works harder to accomplish the same amount

  • as a normal brain,

  • and it even temporarily shrinks because of its lack of water.

  • Over-hydration, or hyponatremia,

  • is usually caused by overconsumption of water in a short amount of time.

  • Athletes are often the victims of over-hydration

  • because of complications in regulating water levels

  • in extreme physical conditions.

  • Whereas the dehydrated brain amps up the production of antidiuretic hormone,

  • the over-hydrated brain slows, or even stops, releasing it into the blood.

  • Sodium electrolytes in the body become diluted,

  • causing cells to swell.

  • In severe cases,

  • the kidneys can't keep up with the resulting volumes of dilute urine.

  • Water intoxication then occurs,

  • possibly causing headache,

  • vomiting,

  • and, in rare instances, seizures or death.

  • But that's a pretty extreme situation.

  • On a normal, day-to-day basis,

  • maintaining a well-hydrated system is easy to manage

  • for those of us fortunate enough to have access to clean drinking water.

  • For a long time, conventional wisdom said that we should drink eight glasses a day.

  • That estimate has since been fine-tuned.

  • Now, the consensus is that the amount of water we need to imbibe

  • depends largely on our weight and environment.

  • The recommended daily intake varies from between 2.5-3.7 liters of water for men,

  • and about 2-2.7 liters for women,

  • a range that is pushed up or down if we are healthy,

  • active,

  • old,

  • or overheating.

  • While water is the healthiest hydrator,

  • other beverages,

  • even those with caffeine like coffee or tea,

  • replenish fluids as well.

  • And water within food makes up about a fifth of our daily H20 intake.

  • Fruits and vegetables like strawberries,

  • cucumbers,

  • and even broccoli are over 90% water,

  • and can supplement liquid intake while providing valuable nutrients and fiber.

  • Drinking well might also have various long-term benefits.

  • Studies have shown that optimal hydration can lower the chance of stroke,

  • help manage diabetes,

  • and potentially reduce the risk of certain types of cancer.

  • No matter what, getting the right amount of liquid makes a world of difference

  • in how you'll feel,

  • think,

  • and function day to day.

Water is virtually everywhere,

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B2 US TED-Ed water hydration brain urine intake

【TED-Ed】What would happen if you didn’t drink water? - Mia Nacamulli

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    Rudy posted on 2016/04/02
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