字幕列表 影片播放 列印英文字幕 They say you need a brain to get ahead, but I already have a head! Hey brain dead chickens, Jules here for Dnews! There’s an old urban legend that a farmer in Colorado cut the head off a chicken with an axe, but instead of bleeding to death and being ground into chicken nuggets, the chicken survived, headless, and just kept running around. It sounds pretty crazy, but it’s just crazy enough to true, and it actually did happen at least once, in 1945. Not only did the chicken survive, it went on to live another, very famous, 18 months. So, do chickens not actually need their heads? Well, frankly, not most of it. When Mike the chicken had his head lopped off, the axe missed two very vital parts: the jugular vein, and the brain stem. It also missed one of his ears but that wasn’t particularly important to his survival. So while Mike was missing pretty much every part of his higher brain centers; the lower part, which regulates things like breathing and heart rate, was still mostly intact. And with a blood supply to keep it going. There were some things Mike wouldn’t be able to do, like math, but since the brain stem attached directly to the spine, in both chickens and humans, it could react to stimuli and keep the body in homeostasis, and well… not dead. In fact, a human can technically survive without most of their brain. In 2001, a boy named Trevor Judge Waltrip was born with a rare condition called “hydranencephaly”. This is where the skull is filled with sacs of cerebrospinal fluid instead of the brain’s cerebral hemispheres, which is the vast majority of what we think of as “brain”. But despite effectively only having a brain-stem, Trevor lived to the age of 12. Just like with Mike, Trevor was able to breathe, maintain a heartbeat, and respond to basic stimuli. And on an aside, simply not having a head doesn’t mean you’re immediately dead. Back when people got their heads cut off by guillotines, when France was cool, there were anecdotal stories about body-less heads able to move their eyes, open their mouths as if to speak, and blink for up to 30 seconds. But today, scientists think that the brain really only has a few seconds after being removed from the body, and thus a source blood and oxygen, before falling into a coma and dying. Any action after those few seconds is most likely a muscular reaction. The same happens in chickens. It’s not uncommon for a headless chicken, even one missing its brainstem, to run around for a little while after decapitation. The headless chicken’s muscles can continue to contract for a short while without a brain telling them to do so. And humans and chickens are not the only animals technically able to survive without a head. Cockroaches can also cheat death, because they’re designed differently from us. When a human or chicken heart beats, it pumps blood around the body to give it the energy and oxygen it needs. And one of the many things that happens when you're decapitated is you lose a lot of blood, and your blood pressure drops, and your heart can’t keep up. But cockroaches don’t rely on blood pressure. Cockroaches and many other invertebrates have something called an open circulatory system, where instead of going through blood vessels, the blood floats just around in the body cavities and makes direct contact with the internal tissues and organs. That means that when a cockroach is decapitated, the threat of the loss of blood pressure is not that big of a deal. Moreover, the roach can keep breathing with the brain entirely. Roach breath comes in through holes along the body segment called called spiracles, that send air to the cells that need it. And because they don’t need to eat as often as humans, roaches they can survive weeks without a head. This gives you a living, breathing, headless cockroach. Ok, I think my nightmares are set for the week. No domain extension will help you tell your story like a DOT COM or DOT NET domain name. And because you watch DNews, you can get 15% off Domain Dot Com’s names and web hosting by using the code DNews when you check out. So back to cockroaches -- why do they even exist? Do they actually have a benefit to nature? We have that answer right here. So do you have any other general science questions? Let us know down below in the comments and don't forget to like and subscribe to DNews for more episodes everyday of the week.
B1 中級 沒有頭的雞真的能活嗎? (Can A Chicken Really Live Without A Head?) 72 5 Jack 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字