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【听力文摘】为铁元素而战

2014-12-29    来源:普特英语听力    【      美国外教 在线口语培训
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The Battle Over Iron

We all know we need iron to live. How else would our blood carry oxygen to our lungs? And cells need iron in order to multiply. The problem is that our cells aren’t the only ones who need iron in order to thrive. Cancer cells and harmful microorganisms like E. Coli and staph need iron, too.

Line of Defense
The good news is that our bodies have several mechanisms for preventing dangerous invaders from getting the iron they need. Our bodies’ defense strategy is to starve these invaders and contain them.

First, the level of iron in our blood plasma drops down dramatically, and our bodies reduce the amount of iron we absorb from our diet to a bare minimum until the danger is over. Next, our white blood cells have a protein that scavenges for loose iron atoms so that the invaders don’t get a hold of them. Finally, to seal the deal, our immune system forms antibodies to the protein receptors the invaders use to acquire iron. The next time the same organism invades, these antibodies will completely block it from getting the iron it needs.

Pumping (Too Much) Iron
No wonder, then, that having too much iron in your system can mean the difference between life and death. Too much iron clogs our bodies’ natural debris-control system and suppresses our white blood cells. What’s more, iron is a powerful oxidant, so when iron reacts with oxygen, it can damage the DNA in our cells and actually trigger the cancer process.


Help your body protect you by making sure that you’re not consuming too much iron. Avoid iron supplements unless your doctor prescribes them, and stop smoking. Tobacco is loaded with iron.

为铁元素而战

众所周知,铁是我们不可或缺的微量元素。如果不是通过铁元素,我们的血液怎么能把氧气送入肺部呢?细胞分裂也需要铁元素的协助。但问题是,不仅正常细胞需要铁元素帮助繁殖,癌细胞的分裂以及像大肠杆菌和葡萄球菌这样的有害微生物的滋生也需要铁元素。

防线

幸运的是,我们人体内有一些防御机制可以抵御有害入侵者,防止他们获取所需的铁元素。我们人体对入侵者采取的防御战略是:断其粮草、形成牵制。

首先,我们血浆中的铁含量会急剧下降,同时我们的身体会尽量减少饮食中对铁的吸收,直到危险解除。接下来,我们白血球中所含的一种蛋白质会清理游离的铁原子,这样入侵者就无法得到铁。最后,为永绝后患,我们的免疫系统对入侵者用来捕获铁元素的蛋白受体形成抗体。当微生物再次入侵时,它将会被这些抗体彻底阻挡在外,从而无法获取所需的铁。

过量摄入铁元素

另外,我们也不难理解为什么人体内铁元素过量将事关生死。大量的铁元素会使人体自身对自由基的控制受阻并抑制白血球生长繁殖。此外,铁具有强氧化性,因此当其与氧气发生反应时,可以破坏细胞中的DNA,从而引发癌变。

确保不要过量摄入铁元素有助于你的机体对你形成保护。在未经医嘱的情况下,尽量不要补铁,并且要戒烟,因为烟草中富含铁元素。

 【本译文由普特网友 九皋子  提供】



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