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  • Lead is a sneaky little element.

  • It’s malleable and durable, so it’s no wonder that for years we used it in piping

  • and added it to paint.

  • But it’s also extremely poisonous.

  • It can create problems all over the bodyfrom rashes, to abdominal pain, to anemia.

  • But the most serious effects occur in the brainand especially in the brains of children.

  • It can cause headaches, memory loss, learning disabilities, behavioral issues, and seizures.

  • And kids don’t even have to be exposed directly.

  • Women who wind up ingesting lead can store it in their bones.

  • And if they get pregnant, that lead can be passed on and damage the brains of their children.

  • Lead poisoning is still a big problem in the US todayand not just in communities you

  • may have heard of, like Flint, Michigan.

  • So, what’s actually happening to the brain when you have lead poisoning?

  • And is there anything we can do to stop it?

  • I’m Anna and this is Gross Science.

  • Lead messes with our brains in a few different ways.

  • But to understand what they are, let’s look really quickly at how brain cellsor neuronscommunicate:

  • and I promise, this will be short, sweet, and hopefully deeply enlightening.

  • Ok, so neurons have a long tail called anaxonat one end, and branch-like structures

  • calleddendritesat the other.

  • They talk to one another when the axon from one cell sends chemical signals to another

  • cell’s dendrites.

  • The receiving cell can then pass the message on to yet another neuron.

  • And all that communicating happens in this tiny gap between the cells called thesynapse.”

  • One thing lead can do is block those chemical signals from being sent, which sounds bad

  • enough.

  • But, lead does another thing that can have even more long-term effects.

  • It can make the synapsethat connection between your neuronsbecome weaker over

  • time.

  • You see, in order for neurons to maintain a strong connection, the axon needs to know

  • that the dendrite is receiving its messages.

  • So the dendrite produces a molecule that lets the axon know it’s being heard loud and

  • clear.

  • That molecule is called BDNF, and you can kind of think of it like the best-friends

  • molecule.

  • It makes the axon and dendrite’s relationship even stronger.

  • But, in order for the cell to produce BDNF, it needs calcium.

  • Calcium usually enters the dendrite through channels, which act like a door that opens

  • for a little while when a signal is received.

  • When the door’s unlocked by the right set of molecules, calcium flows through freely.

  • But when lead’s present, it jams the door, preventing calcium from entering and keeping

  • BDNF from being made.

  • That means that the connections between brain cells start to wither.

  • In adults, having poor connections between your neurons is harmful enough.

  • But in children, with their fast growing brains, it’s especially dangerousnot to mention

  • that the amount of lead needed to cause brain damage in kids is much smaller, in part because

  • their brains are making (and removing) new connections at much faster rates.

  • Sadly, in the past there haven’t been great treatments for lead poisoningand especially

  • not for its effects on the brain.

  • But recently, scientists have shown that simply by adding a BDNF substitute, neurons may be

  • able to bounce back.

  • Here’s a video showing this process in action.

  • On the left are normal cells, in the middle are cells exposed to lead, and on the right

  • are cells exposed to lead that have been given BDNF.

  • When the green dye disappears, it means that the neurons are able to send their chemical

  • signalsso when the video turns black you know everything’s working properly.

  • You can see that the green starts to disappear in the cells with additional BDNF, even though

  • theyve been exposed to lead.

  • Now, were still far from using BDNF as a cure for lead poisoningthis isn’t even

  • being tested on humans yet.

  • Certainly, preventing the exposure to lead in the first place should be the primary goal.

  • But this research offers hope that one day, lead poisoning may be much more treatable.

  • And that’s a great thing, since today, at least 4 million American households with kids

  • are exposed to high levels of lead.

  • And that’s gross.

  • Ew.

Lead is a sneaky little element.

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B2 中高級 美國腔

鉛中毒對大腦有什麼影響? (What Does Lead Poisoning Do To Your Brain?)

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    Jost Lin 發佈於 2021 年 01 月 14 日
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