Description: 

Water is essentially everywhere in our world, and the average human is composed 

of between 55 and 60% water. So what role does water play in our bodies, 

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

Transcription:

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.

Questions:

1. How much water do humans compose? How much to babies compose? 

2. Detail the role of water play in our bodies. For what reason why we still 

   need to drink water? 

3. Enumerate the long term benefits of water intake.