The effects of underwater pressure on the body – Neosha S Kashef

The effects of underwater pressure on the body – Neosha S Kashef


Sometimes when a fish
is reeled up to the surface it will appear inflated, with its eyes bulging out of their sockets and its stomach
projecting out of its mouth, as if its been blown up like a balloon. This type of bodily damage,
caused by rapid changes in pressure, is called barotrauma. Under the sea, pressure increases
by 14.7 pounds per square inch for every 33 foot increase in depth. So, take the yelloweye rockfish, which can live as deep as 1800 feet, where there’s over 800 pounds of pressure
on every square inch. That’s equivalent to the weight of a
polar bear balancing on a quarter. Now, Boyle’s gas law states that the volume of a gas
is inversely related to pressure. So, any air-filled spaces,
like a rockfish’s swim bladder, or human lungs, will compress as they descend deeper and expand as they ascend. After a fish bites a fisherman’s hook
and is quickly reeled up to the surface, the air in its swim bladder
begins to expand. Its rapid expansion actually forces
the fish’s stomach out of its mouth, while the increased internal pressure
pushes its eyes out of their sockets, a condition called exophthalmia. Sometimes rockfish eyes will even have
a crystallized appearance from corneal emphysemas, little gas bubbles
that build up inside the cornea. Thankfully, a scuba diver doesn’t have
a closed swim bladder to worry about. A diver can regulate pressure in her lungs
by breathing out as she ascends, but must be wary of other laws of physics
that are at play under the sea. Henry’s law states that the amount
of a gas that dissolves in a liquid is proportional to its partial pressure. The air a diver breathes is 78% nitrogen. At a higher pressure under the sea, the nitrogen from the air in a scuba tank diffuses into a diver’s tissues in greater
concentrations than it would on land. If the diver ascends too quickly, this built up nitrogen
can come out of solution and form microbubbles in her tissues,
blood and joints, causing decompression sickness,
aka the bends. This is similar to the fizz
of carbon dioxide coming out of your soda. Gas comes out of solution
when the pressure’s released. But for a diver, the bubbles
cause severe pain and sometimes even death. Divers avoid falling victim to the bends
by rising slowly and taking breaks along the way,
called decompression stops, so the gas has time to diffuse
back out of their tissues and to be released through their breath. Just as a diver needs decompression, for a fish to recover,
it needs recompression, which can be accomplished
by putting it back in the sea. But that doesn’t mean that fish
should just be tossed overboard. An inflated body will float and get scooped up by a hungry sea lion
or pecked at by seagulls. There’s a common myth that piercing its stomach
with a needle will let air escape, allowing the fish to swim
back down on its own. But that is one balloon
that shouldn’t be popped. To return a fish properly to its habitat, fisherman can use
a descending device instead to lower it on a fishing line
and release it at the right depth. As it heads home and recompression
reduces gas volume, its eyes can return
to their sockets and heal, and its stomach can move back into place. This fish will live to see another day, once more free to swim, eat, reproduce
and replenish the population.

100 Replies to “The effects of underwater pressure on the body – Neosha S Kashef”

  1. Rabble rabble rabble! Use the metric system!

    Im just kidding. I can understand either system when referred to and do not care either way. 

  2. This fish lives at 55 bars of pressure, when you bring it outof the water it's suddenly only at 1 bar of pressure, a difference of 54 Bars.  It's eyes bulge etc, yet it doesn't explode.

    When a human is exposed to the vaccuum of space, it's a drop from 1 bar of pressure to 0 bar of pressure, a difference of only 1 bar.  Compare that to the immense 54 bars difference that the fish goes through.  This is why a human exposed to the vaccuum of space does not explode, it's just not enough of a pressure difference.  Humans exploding in space is just a myth.

  3. You go through all the trouble of catching a fish and then you don't even eat it. What bizzaro universe are we living in?

  4. "Excape" is a new word for me! Where do you get the readers for these? I would like my informational videos in the metric system and standard English, I have no qualms if people pronounce "escape" as "excape" in her dialect.

  5. fish will live to see another day? good april fools' day joke! you never see any sunlight on the depth of 500 meters

  6. requote: 

    "If you're going to make an educational video that will be seen all over the world, you should probably be using the international base unit system." – Alexandros Kenich, 3 days ago

  7. I personally prefer the metric system, but sense this video is done by Americans they are free to choose what they prefer, so instead of complaining go make your own video with your favorite system

  8. I wNt to point out that at no point in this video did they ever condemn sport fishing. I find that refreshing. Thanks TED

  9. 中文(简体)chinese screen share,made by myself, for a basic view.
    ======================================
    1
    00:00:07.049 –>00:00:10.164
    有时你会看到,当一条鱼被卷到水面时

    2
    00:00:10.164 –>00:00:12.160
    它会出现膨胀,

    3
    00:00:12.160 –>00:00:14.222
    它的眼睛会鼓出眼眶

    4
    00:00:14.222 –>00:00:16.622
    它的胃会
    伸出它的嘴,

    5
    00:00:16.622 –>00:00:19.289
    仿佛被吹成一个气球。

    6
    00:00:19.289 –>00:00:22.893
    这种类型的身体变化是由水压的迅速变化引起的。

    7
    00:00:22.893 –>00:00:25.433
    被称为气压伤。

    8
    00:00:25.433 –>00:00:30.350
    在海面下,每平方英寸上的压力增大14.7磅,

    9
    00:00:30.350 –>00:00:33.848
    每下潜33英尺。

    10
    00:00:33.848 –>00:00:35.750
    因此,对于黄眼石斑鱼,

    11
    00:00:35.750 –>00:00:38.926
    它可以活在深1800英尺,

    12
    00:00:38.926 –>00:00:43.423
    那里每平方英寸上有超过800磅的压力。

    13
    00:00:43.423 –>00:00:47.854
    这相当于北极熊体重的四分之一。

    14
    00:00:47.854 –>00:00:50.106
    现在,玻意耳气体定律告诉我们

    15
    00:00:50.106 –>00:00:54.416
    该气体的体积反比于压力。

    16
    00:00:54.416 –>00:00:58.366
    所以,任何空气填充的空间,像石斑鱼的鱼鳔,

    17
    00:00:58.366 –>00:01:00.165
    或人体肺部,

    18
    00:01:00.165 –>00:01:02.469
    在他们下降更深时压缩,

    19
    00:01:02.469 –>00:01:05.077
    在他们提升时膨胀。

    20
    00:01:05.077 –>00:01:09.377
    后一条鱼咬了渔夫的鱼钩并迅速升到水表,

    21
    00:01:09.377 –>00:01:12.980
    鱼鳔中的空气开始膨胀。

    22
    00:01:12.980 –>00:01:17.412
    它的快速扩张把鱼的肚子顶出鱼嘴,

    23
    00:01:17.412 –>00:01:22.481
    而增加的内压把它的眼睛退出来,

    24
    00:01:22.481 –>00:01:25.403
    这种情况称为眼球突出。

    25
    00:01:25.403 –>00:01:29.652
    有时石斑鱼的眼睛会甚至有结晶外观

    26
    00:01:29.652 –>00:01:31.895
    因为角膜气肿,

    27
    00:01:31.895 –>00:01:35.567
    角膜内会出现很多小气泡。

    28
    00:01:35.567 –>00:01:40.505
    值得庆幸的是,潜水员不需要为一个封闭的鱼鳔担心。

    29
    00:01:40.505 –>00:01:45.172
    潜水员可调节她的肺部压力,通过呼吸上升,

    30
    00:01:45.172 –>00:01:49.472
    但必须警惕水下的其他物理定律,

    31
    00:01:49.472 –>00:01:53.429
    亨利定律表明溶解在液体中的气体的

    32
    00:01:53.429 –>00:01:56.635
    是正比于它的分压。

    33
    00:01:56.635 –>00:02:00.720
    潜水员呼吸的空气是78%氮气。

    34
    00:02:00.720 –>00:02:02.521
    在海下有更高的压力,

    35
    00:02:02.521 –>00:02:04.957
    从空气中潜水罐中的氮气

    36
    00:02:04.957 –>00:02:10.907
    浓度会比在陆地上扩散到潜水员的组织中更大。

    37
    00:02:10.907 –>00:02:13.245
    如果潜水员上升过快,

    38
    00:02:13.245 –>00:02:16.434
    溶解的氮会从溶液中释放。

    39
    00:02:16.434 –>00:02:20.326
    在她的组织、血液和关节中形成的微泡,

    40
    00:02:20.326 –>00:02:24.491
    导致减压病,又名潜水员病。

    41
    00:02:24.491 –>00:02:28.921
    这类似
    二氧化碳气泡从你的汽水里冒出来。

    42
    00:02:28.921 –>00:02:32.172
    当压力减小,
    溶液里会冒出的气体。

    43
    00:02:32.172 –>00:02:34.872
    但对于一个潜水员,气泡
    引起剧烈疼痛

    44
    00:02:34.872 –>00:02:37.184
    有时甚至死亡。

    45
    00:02:37.184 –>00:02:40.519
    为幸免于潜水员病,潜水员缓慢上升

    46
    00:02:40.519 –>00:02:45.311
    并沿途休息片刻,
    即所谓的减压站,

    47
    00:02:45.311 –>00:02:48.296
    因此气体有时间从自己的组织里扩散

    48
    00:02:48.296 –>00:02:51.026
    并通过他们的呼吸被释放。

    49
    00:02:51.026 –>00:02:53.022
    正如一名潜水员需要减压,

    50
    00:02:53.022 –>00:02:56.427
    对于鱼,它需要再压缩,

    51
    00:02:56.427 –>00:02:59.509
    这可以通过把它放回了大海实现。

    52
    00:02:59.509 –>00:03:02.982
    但是,这并不意味着鱼应该往船外扔。

    53
    00:03:02.982 –>00:03:04.809
    充气的身体会浮在水上

    54
    00:03:04.809 –>00:03:09.196
    并被饥饿的海狮吃掉或者海鸥啄食。

    55
    00:03:09.196 –>00:03:10.495
    有一个通俗的故事

    56
    00:03:10.495 –>00:03:14.384
    即刺穿它的肚子用针将让空气逸出,

    57
    00:03:14.384 –>00:03:17.023
    让鱼自己游回去。

    58
    00:03:17.023 –>00:03:19.910
    但是,它现在是一只气球,不应被弄破。

    59
    00:03:19.910 –>00:03:22.449
    要让鱼返回到正确的栖息地,

    60
    00:03:22.449 –>00:03:25.213
    渔民可以使用下沉设备,

    61
    00:03:25.213 –>00:03:29.902
    用钓鱼线把它降到正确的深度。

    62
    00:03:29.902 –>00:03:32.922
    当它回到家园并且被再压缩,鱼鳔的体积减小,

    63
    00:03:32.922 –>00:03:35.652
    它的眼睛可以返回眼眶,

    64
    00:03:35.652 –>00:03:38.965
    它的胃可以回到原位。

    65
    00:03:38.965 –>00:03:41.153
    这条鱼会活着看到第二天,

    66
    00:03:41.153 –>00:03:46.926
    再次的自由的游泳,觅食,繁衍。

  10. why does everyone hates the imperial system? what is the difference betwwen the imperial system and the metric system?

  11. Very well done. Poses a situation, the problem, and solution in one quick, fluid go. One of my favourites from TED Ed so far.

  12. For people outside the U.S a quick explanation : 14.7 psi = 1 bar. 33 feet = 10 meters.
    When you a you dive down the ocean, each 10 meters have 1 bar of pressure on you (at sea surface which is 0 meters deep, you have the usual atmospheric pressure which is already 1 bar) . It also adds up, meaning : if you're at 10m deep you will feel 2 bars of pressure, if you're 20m deep 3 bars, 30m is 4bars, etc. Cheers 🙂

  13. how did the nitrogen even get in the body? the body shouldnt contain nitrogen, its O2 in and CO2 out no nitrogen, the lungs cant pick it up (right?)

  14. Under the sea,
    Under the sea,

    Down here the pressure,
    Darling, it's better
    Take it from me~

    We are what landfolk loves to cook
    But we're inflated once off the hook.

    Darling it's better,
    Here with high pressure,
    Keeps you at leisure, yet unexploded
    And not too bloated

    Take it from me~

  15. we put animals through so much hell omg I wouldn't even wanna live if my eyes popped outta my head and my stomach was out of my mouth

  16. I'm most concerned with how calm her voice was while saying the line "with its stomach sticking out of its mouth"

  17. What happens if you keep decreasing pressure of water does it turn into airr. What is the least pressure water can be

  18. Who releases fish back into the ocean with a fishing rod lowering it with decompression stops? Lmao I wonder how many do this as opposed to just cutting the line and throwing it back

  19. 33 feet = 1 metre
    14.7 psi = 1 atm
    For every 1 metre depth pressure increases by 1 atm.
    SI unit makes a whole lot of sense than Imperial Unit.

  20. cool video but my main question was WHY does going deeper cause more pressure?
    is it the weight of the water? or difference in gravity? or some sort of chemical that gets more potent at deeper levels????

  21. I’m confused.

    1. Why would Nitrogen dissolve more as you get lower, the water pressure isn’t forcing nitrogen molecules into the blood solution. Because your blood vessels don’t compress under all that pressure…?

    2. Why can’t you just breathe out the nitrogen bubbles once they form in your blood?

  22. Im a scuba diver….this is an awsom and simple vid describing the effects of pressure on living organismes. I know divers from all over the world. none of them have any prob with the units of measure. they are common enough to be understandable everyplace. thanx TED.

  23. For the love of God please learn to use the metric system. It's just painful to watch anything scientific when it isn't in the metric system. No quantity or measurement relates to one another, but in metric, it does.

  24. I fish on oceans and fresh water and never seen a fish float after I toss it over. Maybe that species does that but this sounds fake

  25. When your stomach is compressed with air wants to burp, how pressurized is your stomach? How extra in hPa?
    Ratio of “Ready to burp” stomach:Empty stomach

  26. If the fisherman tosses the inflated fish back into the water to float the predators can get a meal. The circle of life.

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