What would happen if you didn’t drink water? - Mia Nacamulli

21,409,963 views ・ 2016-03-29

TED-Ed


Please double-click on the English subtitles below to play the video.

00:06
Water is virtually everywhere,
0
6505
2302
00:08
from soil moisture and ice caps,
1
8807
2452
00:11
to the cells inside our own bodies.
2
11259
2827
00:14
Depending on factors like location,
3
14086
2095
00:16
fat index,
4
16181
1218
00:17
age,
5
17399
715
00:18
and sex,
6
18114
1088
00:19
the average human is between 55-60% water.
7
19202
4606
00:23
At birth, human babies are even wetter.
8
23808
3216
00:27
Being 75% water, they are swimmingly similar to fish.
9
27024
5283
00:32
But their water composition drops to 65% by their first birthday.
10
32307
5024
00:37
So what role does water play in our bodies,
11
37331
2865
00:40
and how much do we actually need to drink to stay healthy?
12
40196
4092
00:44
The H20 in our bodies works to cushion and lubricate joints,
13
44288
4241
00:48
regulate temperature,
14
48529
1419
00:49
and to nourish the brain and spinal cord.
15
49948
3984
00:53
Water isn't only in our blood.
16
53932
2130
00:56
An adult's brain and heart are almost three quarters water.
17
56062
4448
01:00
That's roughly equivalent to the amount of moisture in a banana.
18
60510
3857
01:04
Lungs are more similar to an apple at 83%.
19
64367
4120
01:08
And even seemingly dry human bones are 31% water.
20
68487
5823
01:14
If we are essentially made of water,
21
74310
1741
01:16
and surrounded by water,
22
76051
1583
01:17
why do we still need to drink so much?
23
77634
2858
01:20
Well, each day we lose two to three liters through our sweat,
24
80492
3801
01:24
urine,
25
84293
934
01:25
and bowel movements,
26
85227
1480
01:26
and even just from breathing.
27
86707
1664
01:28
While these functions are essential to our survival,
28
88371
2488
01:30
we need to compensate for the fluid loss.
29
90859
2447
01:33
Maintaining a balanced water level is essential to avoid dehydration
30
93306
4542
01:37
or over-hydration,
31
97848
1862
01:39
both of which can have devastating effects on overall health.
32
99710
3569
01:43
At first detection of low water levels,
33
103279
2125
01:45
sensory receptors in the brain's hypothalamus
34
105404
2963
01:48
signal the release of antidiuretic hormone.
35
108367
3032
01:51
When it reached the kidneys, it creates aquaporins,
36
111399
3090
01:54
special channels that enable blood to absorb and retain more water,
37
114489
5956
02:00
leading to concentrated, dark urine.
38
120445
2605
02:03
Increased dehydration can cause notable drops in energy,
39
123050
3505
02:06
mood,
40
126555
1031
02:07
skin moisture,
41
127586
1188
02:08
and blood pressure,
42
128774
1424
02:10
as well as signs of cognitive impairment.
43
130198
3054
02:13
A dehydrated brain works harder to accomplish the same amount
44
133252
3958
02:17
as a normal brain,
45
137210
1486
02:18
and it even temporarily shrinks because of its lack of water.
46
138696
3922
02:22
Over-hydration, or hyponatremia,
47
142618
2996
02:25
is usually caused by overconsumption of water in a short amount of time.
48
145614
5055
02:30
Athletes are often the victims of over-hydration
49
150669
2573
02:33
because of complications in regulating water levels
50
153242
3343
02:36
in extreme physical conditions.
51
156585
2678
02:39
Whereas the dehydrated brain amps up the production of antidiuretic hormone,
52
159263
4506
02:43
the over-hydrated brain slows, or even stops, releasing it into the blood.
53
163769
5405
02:49
Sodium electrolytes in the body become diluted,
54
169174
2806
02:51
causing cells to swell.
55
171980
2153
02:54
In severe cases,
56
174133
1451
02:55
the kidneys can't keep up with the resulting volumes of dilute urine.
57
175584
4184
02:59
Water intoxication then occurs,
58
179768
2155
03:01
possibly causing headache,
59
181923
1636
03:03
vomiting,
60
183559
1129
03:04
and, in rare instances, seizures or death.
61
184688
3474
03:08
But that's a pretty extreme situation.
62
188162
2133
03:10
On a normal, day-to-day basis,
63
190295
1767
03:12
maintaining a well-hydrated system is easy to manage
64
192062
3570
03:15
for those of us fortunate enough to have access to clean drinking water.
65
195632
3896
03:19
For a long time, conventional wisdom said that we should drink eight glasses a day.
66
199528
4280
03:23
That estimate has since been fine-tuned.
67
203808
2645
03:26
Now, the consensus is that the amount of water we need to imbibe
68
206453
3792
03:30
depends largely on our weight and environment.
69
210245
2871
03:33
The recommended daily intake varies from between 2.5-3.7 liters of water for men,
70
213116
6500
03:39
and about 2-2.7 liters for women,
71
219616
3186
03:42
a range that is pushed up or down if we are healthy,
72
222802
3346
03:46
active,
73
226148
839
03:46
old,
74
226987
963
03:47
or overheating.
75
227950
1713
03:49
While water is the healthiest hydrator,
76
229663
1859
03:51
other beverages,
77
231522
1095
03:52
even those with caffeine like coffee or tea,
78
232617
2613
03:55
replenish fluids as well.
79
235230
2093
03:57
And water within food makes up about a fifth of our daily H20 intake.
80
237323
4983
04:02
Fruits and vegetables like strawberries,
81
242306
2027
04:04
cucumbers,
82
244333
969
04:05
and even broccoli are over 90% water,
83
245302
3572
04:08
and can supplement liquid intake while providing valuable nutrients and fiber.
84
248874
5245
04:14
Drinking well might also have various long-term benefits.
85
254119
3157
04:17
Studies have shown that optimal hydration can lower the chance of stroke,
86
257276
4342
04:21
help manage diabetes,
87
261618
1489
04:23
and potentially reduce the risk of certain types of cancer.
88
263107
4764
04:27
No matter what, getting the right amount of liquid makes a world of difference
89
267871
4180
04:32
in how you'll feel,
90
272051
1287
04:33
think,
91
273338
867
04:34
and function day to day.
92
274205
1868
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7